Does anyone know...

if there is a soft/hardware device that removes the guitars from a song? I play bass and some songs are really hard to pick out the lines.

No such thing exists. That would be analagous to removing the egg from a cake that's already been baked.

Do a search on 'OOPS'. That can sometimes eliminate or minimize anything that's exactly in the center channel of a stereo mix. That's usually the lead vocal and bass.

That will likely eliminate the bass since bass is usually panned center (old hard panned recordings from the 60's notwithstanding). What he wants is something that just keeps the center channel. His best bet since what he wants can't be done is to minimize the guitars. Look to EQ roll off the upper end so only the fundamentals are left. It will be really dull but you should be able to make out the bass but without it's attack.

Now I know why your answer to my question was so idiotic.

Sounds like you need this...
http://www.musiciansfriend.com/srs7/g=guitar/search/ detail/base_pid/2...

This device can speed up/slow down music and preserve the pitch. It also has a guitar cut feature that removes the guitar from the track so you can hear you. It ain't perfect but it works somewhat.

Cheers and HTH

Sorry posted the guitare version

Here is the bass model...
http://www.musiciansfriend.com/srs7/g=guitar/search/ detail/base_pid/2...

Cheers again