[PyMOL] how to delete frames from a trajectory loaded by the "load_traj" command?

Dear all,

I loaded a gromacs trajetory containing about 1000 frames by the following command in pymol:

load protein.gro
load_traj protein.xtc

I want to use these frames to make a movie. However, I find that the position of the protein in first frame is very different from the other frames some I want to delete the first frame so the protein stays in the same position in all frame. Could you tell me the command of removing the first frame?

Thank you.

Best regards.
Yeping Sun