@Tester Thanks for reaching out.
You need to create different instances for your different environments and deploy using ARM templates as documented in Azure API Management DevOps Resource Kit
For enterprise setup the above should be the best solution but if you don't want to create several instances, you might also try using versions and revisions but this is not meant to be used for different environments. Versions and revisions are important concepts in Azure API Management (APIM) that allow you to manage changes to your APIs without breaking existing clients.
Feel free to get back to me if you have any queries or concerns.