Removing User Assignments
Log in to Salesforce as a system administrator.
From Setup, click User Permissions and then select Permission Sets.
On the list, locate the InCountry User set and click it to open.
Select all users and click Remove Assignment.
Uninstalling App Package
From Setup, click Apps, then click Packaging and select Installed Packages.
On the Installed Packages page, locate the InCountry for Salesforce app.
On the confirmation page, select the Do not save a copy of this package's data after uninstall option.
Select the Yes, I want to uninstall this package and permanently delete all associated components box.
You may encounter the situation when the app package cannot be uninstalled at once due to the modifications in the organization after the app installation including the following:
new layouts in App Builder
new pages in App Builder
In this case, you will see the list of modified items. In order to continue with the app package uninstallation, you will have to roll back these modifications and only then uninstall the app from your Salesforce instance.