I mistakenly Deleted a folder

[lekan]

I mistakenly deleted a folder while using a free version of CCleaner. Please how do i recover it?

[nukecad]

Firstly stop using the drive that the folder was on if you can, the more you use it the more chance that there is of overwriting the deleted files.

Next you will need to try and recover the deleted files, either from the Trash, or from Mac 'Time Machine' if you were using it, or using a file recovery tool.
(Note that CCleaners sister product 'Recuva; does not have a Mac version, so you will need to use an alternative such as 'Disk Drill').

See this for a step-by-step guide to recovering deleted files on a Mac: https://www.ionos.co.uk/digitalguide/server/configuration/mac-recovering-deleted-files/

PS. You should get into the habit of always backing up important files to an external drive. (Such as with Time Machine).
Things do go wrong, you make a mistake, or the drive crashes, or files get corrupted, or ????,  and you lose files - it's then always much easier to restore copies from a backup than it is to try and recover the deleted/lost files.