For OTK 3.x you will need to edit the 'OTK User Role Configuration' policy.
For OTK 4.x you will need to edit the 'OTK User Attribute Look Up Extension' policy.
1. Locate the following 'compare' assertion
2. Edit the compare assertion to include the name of the user you wish to make an administrator separating each id with the pipe character
3. Save and Activate the policy