We're replacing an old sink in one of our bathrooms, and doing so will involve replacing the trap. That's usually easy, but in this case it's not.

It looks to me as if the outlet end of the P-trap is threaded onto the male stub which protrudes from the wall. The stub from the wall is covered entirely by a decorative collar, so I can't get a wrench on it to keep it from turning, and without that access, I won't be surprised if the stub unscrews from the vertical drain pipe inside the wall. The trap is 1-1/4". Maybe I could remove the collar, perhaps with a dremel?

Or maybe I should simply call a plumber for this job, on the assumption that I'll end up calling them anyway, sometime before I'm done? ;-)