Chris – no magic involved – they should just pull out. If I understand you correctly they must be seized due to the ravages of time and muck so a liberal dose of WD40 (other makes of releasing agents are available) ought to do the job.
If possible leave to soak and maybe a few gentle taps with a blunt instrument will also help to free them off.
If they do not respond to gentle persuasion you might try twisting them out with a pair of molegrips (other makes of locking pliers ….etc.). However, if you are intending to re-fit them, take care not to crush the outer sheath onto the cable.
Bernie.