If you imported contacts or companies and realize that something went wrong, there are two possibilities to undo the import. Picking the right one all depends on the amount of time that passed since the original import:
1. You go to the overview of contacts or companies respectively, where you see at the bottom on the righthand side “Import”. Click 'Undo import' to actually undo the import. You have this option for about two weeks after the import if you didn't click on 'OK, dismiss' yet. In general we advise not to click on 'Ok, dismiss' in order to keep the undo option available.
2. In case the import dates back longer than two weeks, you still have the option to work with segments in order to delete the imported contacts or companies. Go to the overview of contacts or companies and create a segment as shown below. The date should equal the day you imported your contacts or companies. Once you created the segment, you can delete al contacts or companies within it by clicking on 'Actions' and selecting 'Delete'. This actions requires admin rights. Note that this segment will also include contacts or companies that were manually added on that day, so watch out!