If you wish to terminate an inter-institutional agreement, you have to find the IIA in the IIA>IIA List menu on the enhanced EWP Dashboard and click on it to open the Single View of it. When you open the Single View of the IIA, find the red button Terminate IIA which is located at the bottom middle and click it.
When you click the Terminate IIA button, a small window will pop up warning you that you are about to terminate an IIA.
After terminating the IIA, your partner will be notified about your termination and you are transferred to the Single View. The new status of the IIA is Terminated by You and you can see the Revert IIA button to be active now.
The last approval remains valid and you can revert it back to its previously state at any time until both of you approve the IIA termination. This can be done with the Revert IIA button which allows you to revert the IIA to the previous version of it where it was in Approved by all status and therefore undo the termination, in case you changed your mind. Learn more on how the Revert IIA button works here (link).
Note that you can only terminate an IIA when it is in Approved by all status.