Hello Jessica,

There is not really an undo of an Import, you just delete the asset imported into the wrong company. See How to delete an asset or multiple assets for more information.

~Delray

Thank you for the advice!  I was able to delete easily.  Since these were the assets newly added at the bottom of the list; when deleting them there should be no gap in numbering should occur, is that correct? 

Yes, that is correct.

~Delray