I installed a new electric fuel pump and pressure regulator on my 88.5 samurai and was wandering how to by pass the mechanical one. The mechanical one has a return line do i need a return line with a electric fuel pump?

It depends on the fuel pump, your pressure regulator might have an outlet valve. The fuel pump I went with did not require a return line, so I just put a couple of bolts in the end of the extra lines and used a hose clamp to keep them in place, just so dust wouldn't get in.  It's not really necessary, but you will likely need the return lines if you ever upgrade to fuel injection.

From your pump just run the line directly into your carb.  I used some rubber caps and just capped off the existing fuel pump, but you can remove it and put a metal place cut to size and a gasket in it's place if you want to look professional.