HI Lanez,
Please check the steps here this is quite easy and - To make a user an administrator of an Azure subscription, an existing billing administrator assigns them the Owner role (an Azure role) at the subscription scope. The Owner role gives the user full access to all resources in the subscription, including the right to delegate access to others.
Hope this helps.
JS
==
Please Accept the answer if the information helped you. This will help us and others in the community as well.