By taking admission in a college for bcom via Mumbai uni I get a college so am I removed from the process or wait for other clg Merit list?

No it never happens this way. Let me explain you the process.

If you supposedly fill one college's aaplication form and take admission there and wait for other colleges' merit list to release, then if you changed your mind or now have a better option of college or college of your choice, you can simply get the college application cancelled in the previous college where you took admission and then take admission in the other one. There is a very easy process to cancel the previous one. You can consult the college authorities for the same. They will always help you.

Note- You cannot take admission in some other college while you have not cancelled your previous college's application. It is a must. You cannot apply for two colleges at the same time.