True Image 2013 - Deleting old backups

Consider a different approach. Stop using the old task and create a new task but with a new custom backup scheme which includes "automatic cleanup". This setting will enable the program to do its own regular cleanup and deletion of old files.

If your backup type is just for "full" only, then review signature lnk 2 below and look at the illustration 11-Full.
The illustration shows keeping 4 backups on a revolving chain ( new added and then old deleted--keep 4) but you can use a different figure for how many fulls you want to keep.
Here is the illustation for keeping 4 with automatic deletion. The link 2 also shows illustations on keeeping inc or diff types as well.

Figure 11-Full: Example of custom/full backup method settingsIf using Full backups only, this is a recommended method. These automatic cleanup settings will provide for automatic deletion of the oldest backups after the "Store no more than X number of chains" quota has been reached.
In this example, deletion of oldest backup will occur immediately following creation of backup #5.

Allow space for 1 more full backup in addition to "Store no more than X number of chains" as the program will NOT delete the oldest full until its replacement has been successfully created.

Review this next link regarding the deletion of backups from within the program . Deletions done from this screen within the progam should prevent the "backups missing" error messages as well.
http://forum.acronis.com/system/files/delete-backup-file.jpg

Sorry, did not mean to comment here, and am not sure how to delete this. My bad!

Sis-sis,
You need to start over with a new task with different custom scheme parameters.
Unwanted existing backups will need to be deleted manually via Window Explorer.

It is possible to get a task working which will automatically delete the older files it creates as the older files meet the criteria for deletion.

Here are some general rules which I practice.

AGH-1. 64640: Do's & Don'ts--Hints to help prevent issues with your TIB backup files creation. New

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I have better success by NOT using the "delete chains older than X DAYS" ,
    but instead, use the cleanup option "store no more than X chains". This GH12 example below shows you how.
Remember, the program does not consider whether to perform the deletes until AFTER the scheduled backup has been completed, and the deletion is always the oldest complete chain.

Based on your specs of daily backups with a new full every 10 days, your chain length is 10 files (1 full + 9 inc);
If you would change my example of 6 inc to 9 inc,
    and change my example of keep 4 to "store no more 2 CHAINS" (you may wish this to be only 1 or possibly 3), the result would be

If you set it to "store no more than 1 chains,
    deletion of oldest chain (chain 1, 10 files) would occur immediately after sequential backup #11, leaving 1 tib
If you set it to "store no more than 2 chains,
     deletion of oldest chain (chain 1, 10 files) would occur immediately after sequential backup #21, leaving 11 tib
If you set it to "store no more than 3 chains,
     deletion of oldest chain (chain 1, 10 files) would occur immediately after sequential backup #31. leaving 21 tib

Following each deletion, all existing tib would remain and the daily backups would resume the next day as scheduled with whatever backup slice is next due.
If you have the storage space, keep as many chains as space permits, Don't be in too big a hurry to have the older files deleted as it is often them which has what you may need.

GH12. Create Custom Incremental Backup Scheme. 6 Inc, Keep 4 chains. The 6-4 is an example only with user choice for whatever number of chains to be retained best fits the individual needs.

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Not my recommendation, but If you choose to use the option "delete versions older than "x" DAYS

If you set it to "delete versions older than "1" DAYS", deletion of oldest chain (chain 1, 10 files)
     would occur immediately after sequential backup #11, leaving 1 tib full b2
If you set it to "delete versions older than "2" DAYS", deletion of oldest chain (chain 1, 10 files)
     would occur immediately after sequential backup #12, leaving 2 tib full b2 + Inc s2
If you set it to "delete versions older than "3" DAYS", deletion of oldest chain (chain 1, 10 files)
    would occur immediately after sequential backup #13. leaving 3 tib full b2 + Inc s2_s3
If you set it to "delete versions older than "4" DAYS", deletion of oldest chain (chain 1, 10 files)
    would occur immediately after sequential backup #14. leaving 4 tib full b2 + Inc s2_s4
If you set it to "delete versions older than "5" DAYS", deletion of oldest chain (chain 1, 10 files)
    would occur immediately after sequential backup #15, leaving 6 tib Full b2 + Inc s2_s5
If you set it to "delete versions older than "6" DAYS", deletion of oldest chain (chain 1, 10 files)
     would occur immediately after sequential backup #16, leaving 7 tib full b2 + Inc s2_s6
If you set it to "delete versions older than "7" DAYS", deletion of oldest chain (chain 1, 10 files)
    would occur immediately after sequential backup #17. leaving 8 tib full b2 + Inc s2_s7
If you set it to "delete versions older than "8" DAYS", deletion of oldest chain (chain 1, 10 files)
     would occur immediately after sequential backup #18. leaving 9 tib full b2 + Inc s2_s8
If you set it to "delete versions older than "9" DAYS", deletion of oldest chain (chain 1, 10 files)
    would occur immediately after sequential backup #19, leaving 10 tib full b2 +Inc s2_s9
If you set it to "delete version older than "10" DAYS", deletion of oldest chain (chain 1, 10 files)
    would occur immediately after sequential backup #20, leaving 11 tib full b2 +Inc s2_s10

Following each deletion, all existing tib would remain and the daily backups would resume the next day as scheduled with whatever backup slice is next due.
Remember, the program always creates the replacement first, before any considering deletion rules.