Should i buy a multi (1-4) to flip with or without tenants?

I’m looking to buy multi-family homes(1-4 units) with the intention of rehabbing and reselling. my question is, 1) Is it possible to buy should a multi with still tenants in it and still do rehab and resell? If yes, how do you do rehab while there are still tenants in it? 2) Or should i only buy vacant multis if my intention is to flip them.

I have about 35 units right now and many of them were bought with the intention of flipping and I keep tenants in them just to pay off the bank. It has worked out very well. 8 of the homes that i have flipped this year were tenant occupied with month to month leases.