Visit your [My Agency] tab and click [Add Agent +] button to add the person who will be replacing you (see screenshot here). You will need his/her name and email address at a minimum. 

Once added, click the EDIT link next to his/her name (screenshot) and adjust the "Role" to the same level you are at. For example, if you are in the "network administrator" role, then change this new agent from the "Agent" role to that same level (see screenshot here). Save changes. 

*NOTE* If you were the primary network administrator, you will also need to assign the new agent (or someone else on the network) to become the new primary network administrator. Visit [Admin] tab >> EDIT NETWORK SETTINGS link (see screenshot here) >> and select another network administrator from the "Primary Admin" drop-down list (screenshot)...Save changes.

Next, update your billing information (if necessary). If the credit card on file needs to be updated or the name listed on the billing account should change please do so now. Go to your [My Agency] tab and click the [Billing] sub-tab to update all appropriate billing and contact information (see screenshot here). 

Lastly, disable your access by visiting the [My Agency] tab, [General] sub-tab and click EDIT next to YOUR name (see screenshot here) and check the check-box that reads "Disable login for this agent?" (screenshot)... Save changes.

When you Log Out of the system or close your browser you will no longer have access.