Precision 5820 Boot problem

Can anyone tell how I can disable booting to a redundant domain.

I simply need to boot from the local drive, which does still contain the username and password I used origionally.

Changing PXE settings in the BIOS seems to have no effect.

I have a recovery USB to restore to as new, but there's personal items on the drive I don't want to loose.

Any help will be extremely appreciated.

Please note I'm in the UK, so there may be some lag with any replies I need to make.