Uninstalling Reports for Work means removing the permission to Reports for Work (remove the permission yoou granted to Reports for Work to run with your Google account).
After uninstalling Reports for Work, you will no more able to use this tool. You can of course autorize it again ;-). The data stored in your Google Drive will not be affected, the Spreadsheets used by Reports for Work will not be deleted.
There are 2 ways to uninstall Reports for Work
Use the email received on first installation
Find the mail received and click on “Uninstall” button
Go to Google account security settings
Go to https://security.google.com/settings/security/permissions and find Reports for Work, then click “Remove” button