If you need to uninstall and reinstall your authorized copy of ArcGIS (for example, if you are reformatting your hard drive or switching to a new computer or you have entered your eva code in once and it did not authorize) please follow these instructions before uninstalling the software.
- Open up ArcGIS Administrator (located in the ArcGIS program group in your Start Menu).
- In the left-hand pane, click the Support Operations folder, and the Deauthorize button.
- Follow the instructions to remove the core product and any selected extensions from your machine. https://desktop.arcgis.com/en/desktop/latest/get-started/administering-desktop/authorizing-arcgis-single-use-products-and-features.htm\
- Uninstall ArcGIS for Desktop (Control Panel > Programs and Features).
- Reinstall ArcGIS for Desktop.
- Authorize software.