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.
You will have to wait then for the partner first to approve the termination you requested. After the partner has approved your request, the status of the IIA will be Termination Approved by Partner and it will be your turn to approve by clicking the Approve Termination button.
When you click the Approve Termination button a small window will pop up warning you that you are about to approve the termination of the IIA. You may proceed or cancel if you changed your mind.
After you confirm the approval of termination, the new status of the IIA is Termination Approved by All.
After the IIA is terminated, there is no option to revert it but in case you decide that you need it again and you want to use it, you may modify it and send it to the partner for approval. After the IIA is mutually approved it may be considered again as valid and the agreement in effect. More information on how to Modify IIA can be found here https://esci-sd.atlassian.net/wiki/x/AgCpEg.
Note that you can only terminate an IIA if it is in Approved by all status.