If the job is linked to a purchase order, go to the purchase order and,in View mode, right click in the job number field and select Unallocate Stock.
If the job is linked to another job:
•Go to Tools > Options > Jobs, and untick Show Quote # instead of Ex.job.
•Log off and back on. The Quote# field in the job will now show the Ex.Job#.
•Edit the job and remove the Ex.Job#.
•You will then need to change the Job options (1. above) back, if necessary.
Further information: