Follow the steps given below to uninstall Lead Assignment and Distribution Automation from your Dynamics CRM:
To uninstall the solution, at first you need to disable all the Assignment Configuration Records.
1) Navigate to Lead Assignment and Distribution Automation --> Registration -- > Enable Assignment Configuration. Next, disable all selected entities and click on Save.
2) Ensure that Selected Entities column is blank.
Now, navigate to Settings --> Solutions --> Select Lead Assignment and Distribution Automation solution.
Click on delete button. A pop-up will appear asking for your confirmation. Click on OK and the solution will be uninstalled from your environment.