In LiteSpeed 5.x maintenance plans there are two ways to remove old backup files: the Clean up maintenance plans task (which is only available for SSIS plans) and the Remove files older than option in the Back Up Database task.
The Clean up maintenance plans task removes LiteSpeed 4.8 and LiteSpeed 5.x backup files. The Remove files older than option removes both LiteSpeed 4.8 and LiteSpeed 5.x backup files for legacy plans. However, for SSIS maintenance plans it only removes LiteSpeed 5.x backup files.
WORKAROUND:
For SSIS plans, the Clean up maintenance plans task to remove LiteSpeed backup files created in Versions 4.8 and 5.x
Use Remove files older than option in LiteSpeed maintenance plan option to remove both LiteSpeed 4.8 and LiteSpeed 5.x backup files for legacy plans.
See Release Notes for LiteSpeed Version 5.x:
https://support.quest.com/SUPPORT/index?page=productInformation&pid=PR268442521&question_product=LiteSpeed%20for%20SQL%20Server
