When you remove the K2 for SharePoint App from a SharePoint site collection, there are still bits and pieces of the site collection left in SharePoint and in K2. These should get removed completely from both SharePoint and K2.
When removing the K2 for SharePoint App from a SharePoint site collection, perform the following steps:
We do have a PowerShell script that does some (but not all) of the clean-up for you. If you would like the clean-up script, please log a new support ticket, reference this KB and request the clean-up script.
We have logged an item for the development team to look at. All of the clean-up should be added to a future build of K2. (At the time of writing, there is no official date that will include this clean-up functionality.)
The first download is for K2 4.7 and K2 Five 5.0, 5.1 and 5.2.
The second download is for K2 5.3 and K2 Cloud Update 8 and 9 and possibly later. Untested but should work for K2 Five 5.0, 5.1, 5.2 and 5.3.