Some of them will automatically reapply that read only because of Windows built in defenses (SFP for example.) It's a shame you didn't reveal the folder name or see if your account is one of the owners of that folder or the ROOT folder.
Again, all this is well discussed so I can't duplicate NTFS permissions at length but you do know that a folder is in the folder above it so you must have permission in the folder above this folder to make the change. Some folk have forgotten the NTFS and other basics or are just starting.
I can't tell where you are in your journey.
I have a directory right under the C driver. I don't know how it is set as read only. I have tried to remove the restriction either through UI, that is un-selecting the check box, and on the commend line with "attribe -r +s <directory>". None of them work although I sign in as the administrator.
How to solve this problem?