You would have to let your IVA fail by missing three payments.
Is there a reason why you wish to stop it?
If you're struggling, then you should speak to your IP in the first instance.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk