rm: cannot remove - Permission denied

I cannot see anything in what you posted that points to the cause. It does, however, rule out the most obvious causes.

It may be worth looking into SELinux.

Run the following to check current level of enforcement:

/usr/sbin/getenforce

If it says "Enforcing", this could possibly be part of the equation. Then try temporarily disabling SELinux with:

/usr/sbin/setenforce 0

Any difference?