Hi,
In the Azure portal, navigate to API Management Services using link below:
Click on your API Management Service instance, then in left pane under Deployment + infrastructure click on Gateways. If you have self-hosted gateways they will be listed here. Keep in mind you can use both managed gateway as well as self-hosted gateways.
API Management in a Hybrid and MultiCloud World
If the above is useful please click Accept Answer.
Thanks.
-TP