so it is easy , try to download TextPipe here on BHW it can manage easily several GB files and I would try to convert it in txt file , if this would be difficult TextPipe maybe should remove this pattern also directly from .sql file.
TextPipe has a filter for removing text pattern together with whole line which belongs to that string.
1.It is something like this :
Filters\Remove\Remove lines\Remove matching lines (1 the same unwanted text or \Remove lines from a list(more unwanted patterns)
It will remove the lines from several GB file in few minutes
or second option :
2.if you want only exact text (not lines where lives that string)so use find and replace :
Filters\Replace\Find EasyPattern
find your string and replace with "nothing" and it will find you all hundreds or thousands strings and it will change that to nothing