Is there a way to run a  brushless motor using a power supply apart from a lipo battery?  let's say the motor runs on 3s and 4s lipo and the suggested ESC 30A!
My plan is to connect the ESC to a power supply and not a lipo battery! So is it possible to get a separate power supply?

Yeah it will run without any problem I have tested it with lead acid batteries. And it will work also work with any supply without any issue.Take care that source resistance is in permissible limits so that when drawing high current there wont be high voltage drop thereby creating a under voltage.

Yes it should be possible to run a brushless motor and an ESC off any power supply as long as it can supply enough current (and ideally the ESC should have enough filtering). However, if the ESC has active braking there is a good chance it will damage the power supply due to reverse current spikes.

Yes i use my computer smps psu as a bench test supply