If you leave the window up, then leave the regulator hooked up to the window (leave the arm and roller IN the channel that's connected to the bottom of the glass) and you can remove the motor from the regulator. The window glass and the fact that the regulator is bolted down will prevent the assist spring from creating havoc in the door panel if you were to try to remove the motor from the regulator in the door with the regulator arm not in the glass channel. If you did that, the arm would whip around, and possibly cut your fingers off.
The caveat of trying to remove the motor from the regulator is that the bolts that hold it down are hard to get at in the door. This is why people wind up unbolting the regulator, and then try to remove the motor with disastrous results.
Best bet, since it's the front door (and it's WAY easier to remove the regulator from a 2 door door rather than the rear quarter!), is to put the window up, and put something through a hole in the door panel frame to hold the glass up (like a screw driver shaft) once the regulator is removed and isn't holding up the glass. Unbolt the regulator assembly (don't touch the motor bolts), and as noted above, remove the entire regulator and motor assembly from the door. You'll need to slide the regulator forward or back to get the roller out of the track on the bottom of the glass.
However, BEFORE you go to all the trouble to do this, try testing the assembly to see if the problem is NOT the motor.
Disconnect the motor from the wiring harness - unplug the motor connector from the wiring coming to it from the switch. The motor operates with a common ground (motor bolted to the car body), and one wire in the connector is UP, and the other DOWN. Using a stand alone 12V battery, connect the Negative to a bolt on the door, and then connect 12V Positive alternatively to each tab on the motor pigtail. If the motor moves, then the motor is not the problem, and the issue exists further back towards the switch. At this point you'll need to see if there are wires pinched etc., between the switch and the motor. When going through wiring, always disconnect the car's battery first. This is especially important with the power windows, as they're always hot, even with the key off and out.
Likely though, from your description, the issue IS the motor, and it needs to be replaced or rebuilt. So, if testing proves the motor is at fault, remove the whole regulator and motor assembly from the door as described above.
Once you have it on the bench, removing the motor from the regulator has its own dangers, as noted above in
@bronze turbine's post. Immobilize the regulator arm so that the assist spring does not make the arm swing around when you remove the motor bolts. Some arms have holes in them to put a bolt through, or clamp the regulator down in the vice to prevent movement.
Safety first in this instance.