Example operation:

Original text:

```
% echo -e "This is number 800 with decimal;other stuff\n44333; more data"
This is number 800 with decimal;other stuff
44333; more data

```

Desired awk result:

```
% echo -e "This is number 800 with decimal;other stuff\n44333; more data" | awk
;other stuff
; more data

```

UPDATE: after all answers: the separator ';' is only once per line and will exist if line exists, so my solution will always work, but it's not as universal as others solutions (which consider blank lines, lines with no separator o with more than one).