Manage site collection administrators
This article describes how global admins and SharePoint admins in Office 365 can add and remove site collection admins for any site collection. If you're an owner of a communication site, or a site that belongs to an Office 365 group, see Manage your SharePoint site settings for info about giving people access to your site. If you're a site collection admin for a classic site, see Manage your SharePoint site settings.
If you're a global admin and want info about assigning other users the SharePoint admin role in Office 365, see Assigning admin permissions.
Add or remove site collection admins
To change the owners of a communication site or new team site, you can use the new SharePoint admin center preview. For info, see Manage sites in the new SharePoint admin center. You can also add and remove group members in the Microsoft 365 admin center. For info, see Add or remove members from Office 365 groups.
To add or remove site collection admins on classic sites, use the classic SharePoint admin center:
Sign in to Office 365 as a global admin or SharePoint admin.
Select the app launcher icon in the upper-left and choose Admin to open the Microsoft 365 admin center. (If you don't see the Admin tile, you don't have Office 365 administrator permissions in your organization.)
In the left pane, choose Admin centers > SharePoint.
Point to the site collection for which you want to change the administrators, and then select the check box in front of it.
Click Owners, and then click Manage Administrators.
Change the name in the Primary Site Collection Administrator box, or add or remove names in the Site Collection Administrators box.
Click Check Names to verify that the user names are valid.
Click OK .