Perform the following steps to approve or reject the tenant registration requests:

Log on to Sigma Studio as admin.
Click the sandwich menu on the left-hand side of the page.
Click Tenant Management.

All tenant registration requests appears under the Tenant Approval section as shown in the following screenshot:
Click Approve or Reject based on your requirement.
The success message appears as shown in the following screenshot if you approve the registration request:

Now, the tenant user will receive a confirmation mail based on the approval or rejection of the project as shown:

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