Don't know for sure, I'm still on Lion (10.7.5), but, can you change Permissions on those files with the Get Info panel, by opening the "lock" (icon) and adding your admin user to the list of Permissions? Click the + box and select the desired user and [OK] that.
I have used Permissions many times for this kind of operation, to move or remove or Send it to .Trash after getting the Permission set.
FYI - Please be aware that in Lion, it usually will not "stick" on the first time you add the user. It often takes 5 or 6 repetitions, and sometimes 15 or more, before the user will be shown in the Permissions box at bottom of Get Info. After you have the user established, then you must as well, change the other column to "Read & Write" by clicking on the "Read" or whatever it may show, for the new user. And that also often takes several repetitions of the change operation. Count the tries; if it doesn't stick after 16 or 20 tries, I have always quit, but it almost always has worked for me, with enough persistence. Maybe Mountain Lion made some improvement in this area. Good luck.
