I found this article (several years old): https://community.lansweeper.com/t5/general-discussions/mass-delete-ip-address-range-locations/m-p/5...
It states to run a script to remove all IP Ranges, which worked for me. I found the tool DatabaseMaintenance.exe on the host server at Lansweeper\Tools.
The script I ran (also in the link above): "Delete from tsysIPScanRanges where servername ='scanservername'"
If by "delete scanning targets" you mean something other than IP Ranges then I assume you can find the respective table and swap that for "tsysIPScanRanges."