If you imported contacts or companies and realize that something went wrong, you can 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.
In case the import dates back longer than two weeks, you still have the option to work with segments. There you 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.
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