Windows 10 won't let me rename or delete certain folders

An administrator account does not prevent a folder from being locked by a running program, and an in-use message is different from a permissions failure. Since ownership changes and restarting Explorer have not helped, first identify which condition applies to one affected folder. Use Microsoft's Process Explorer handle search, or the Sysinternals Handle utility, to search for its path. If a program has an open handle, save your work and close that program normally, then retry. Do not force-close handles, because Microsoft warns that doing so can destabilize applications or Windows. If no lock is found and the error specifically concerns permissions, inspect that folder's Security, Advanced settings for the actual owner and effective access. Share the exact path and error before changing permissions further. Avoid applying ownership or full-control changes recursively to Windows, Program Files, or an entire drive.