The simplest way is to have your UET tag placed on your website.

Else, you will have to place your UET tag on a page and generate sessions where the UET tag will load. This way Microsoft Ads will verify the UET tag. With the UET Tag Helper you can check if the tag loaded correctly.

It is possible to remove it again afterwards but you will then have to frequently go through the verification process to keep it active. We recommend to have the UET tag active on at least one page that frequently receives some traffic.