Step 1 
In the navigation bar, click System Configuration.
Step 2 Click ACS Certificate Setup.
Cisco Secure ACS displays the Installed Certificate Information table on the ACS Certificate Setup page.
Note If your Cisco Secure ACS has not already been enrolled with a certificate, you do not see the Installed Certificate Information table. Rather, you see the Install new certificate table. If this is the case, you can proceed to Step 5.
Step 3 Click Enroll New Certificate.
A confirmation dialog box appears.
Step 4 To confirm that you intend to enroll a new certificate, click OK.
The existing Cisco Secure ACS certificate is removed and your CTL configuration is erased.
Step 5 You can now install the replacement certificate in the same manner as an original certificate. For detailed steps, see Installing a Cisco Secure ACS Server Certificate.
