Sharepoint - Clear list items and reset id back to 1

Unfortunately, you can't truncate the SharePoint list as you do in the Database Table!

Also, I don't think it's a practical solution to

• Delete the 100 lists then recreate it again or
• Save 100 lists as a template without content then delete the original list then recreate it again!!!

In your scenario, from the beginning, it was supposed to create a SharePoint solution/add-in for all lists definition. Once you have finished the testing phase, just redeploy your solution.

To create A-list Definition

• List definition / list template in the SharePoint add-in model

• How to: Create a Custom List Definition

The only way to reset the ID to start from 1 again is to delete the list and then recreate it.

One way to reset ID in a SharePoint list is that you can save list as template and then use this template to create the list again. The ID will be reset and start from 1.