FWIW, you can just type G00 G90 G54 X0 Y0 Z0

That rapids to your global work coordinate origin (assuming you use the standard G54). You don't have to type G00 X0, G00 Y0, etc. Caution: Some programs read left to right, some one line at a time. It sucks when you rapid right through your clamp, break your tool, break your clamp, lose your origin, and gouge your part. Haha. What I usually do at the beginning of a "manual" program is to rapid up in Z however far to clear all clamps and offsets. Like:

G00 G90 G54 Z5.
X0 Y0
Z0.25 M08
G01 Z-.whatever Fwhatever

Every interface I've encountered remembers the G00 G90 G54, so you don't have to type it every line if you're still moving in rapid. Same for G01, G02, etc.