Removing freewheel MF-Z012 without tools
The answer is in the question - freewheel, not freehub or cassette. You will be needing the tool and a vice (or huge adjustable spanner).

Remember to put the skewer or wheel nuts loosely on to hold the removal tool in place whilst you give it the initial heave-ho. Thereafter take the skewer/nut off.

If you don't want to do it/fork out for the tool then ask your friendly local bike shop - it is a given that they will have the tool. Go with your big adjustable spanner and borrow the tool for five minutes (remembering to buy something) if they insist on charging you £10 for the job.