need help running power cable

[aaaaaahhhhhhhhh]

Hey guys, I tried searching but couldn't find any information to help my current issue. I've already ran my power wire for my amplifier through the passenger firewall, and intend to run it along the passenger side kickpanel, however once I reach the vertical piece which contains the seatbelt, I can't go any further. Am I correct in assuming that i need to remove this vertical piece? any tips on removing this piece or alternative (easier) ways to run this cable? It's a 4 gauge wire if that makes a difference. thanks in advance

2004 6mt s4 sedan