If you import a bad mailing list which hurts your sending reputation (or which even gets your account suspended), you can usually undo the import. This is quite simple:
1) Head over to the "Lists" menu in your E-goi account and hit "Actions" of the list you did the import into.
2) Find your import, click the options button on the right-hand side of the page (under the "Actions" column) and choose "Undo".
That's all there is to it! Your import will be undone, with all imported contacts being removed from the list.