For this you would need the help of our support team. Please make a request here: https://www.uipath.com/contact-technical-and-activations. Select Service request - Licensing.
We follow below steps in my organization to deactivate/release license key from current machine then we can use that key on other machine.
- Go to above link(mentioned by @ovi),
- Raise a request to uipath support,
- Mention your machine/computer name in the description,
- They’ll release license key from database then it’ll be available to use anywhere,
- Activate permanent license using that key.