I don't think your pipe is a vent, but is either a cleanout or marks the distribution box. If that is the case, you can cut it off, but you need to be able to locate it again. Take a look in the pipe. A vent would be open. A cleanout would terminate in a removable cap and a distribution box is probably concrete. If it is a marker to a distribution box/valve, cut the pipe below the surface and record its position by triangulation with other permanent landmarks and precise measurements.