If someone such as a doctor or lawyer is struck off, their name is removed from the official register and they are not allowed to do medical or legal work any more.
[British]
...a company lawyer who had been struck off for dishonest practices. [beVERB-ed PARTICLE]
He could be struck off the medical register. [beVERB-ed PARTICLE]
See full dictionary entry for strike
strike off in British English
verb(transitive)
1.
to remove or erase from (a list, record, etc) by or as if by a stroke of the pen
2. (adverb)
to cut off or separate by or as if by a blow
she was struck off from the inheritance
strike off in American English
1.
to separate, or remove, by or as by a blow or cut
2.
to remove from a record, list, etc.; erase; expunge