The best bet, do up the bolts again, plug in the power, hit the motor with a hammer as often is the DC motor which is playing up. THis will get the motor running again and allow you to lower the reg to remove it

The reg will not come out wile it is in the complete up position, best to have it 3/4 down

If this fails, grab some side cutters and cut both the cables and this will allow the reg to also drop