The permissions need to be corrected.
It's easier to do a folder of photos at once.
Select the folder - right click for "Get info" cmd-I Check if your username appears at the bottom in Permissions. Click the lock - enter your admin password.
If not, add + yourself and set Read and Write. If you are doing a folder set "Apply to Enclosed items". As a shortcut you may be able to do "Make *yourself* owner"
