This may be well known, but I searched for weeks to figure out how to delete an Exchange Server Source from activesync without connecting to my PC.

You can, of course, delete the server profile through the Activesync client on your desktop.

But, my problem is that I rarely, if ever, connect to my laptop and wanted to be able to change Exchange accounts from my phone.

I am embarassed by how easy this is, but hopefully this will save someone a headache:

Activesync -> Options -> Hilight Exchange Server -> Delete

You can then choose to Add Server Source. Contacts/Tasks/Calendar/Emails are not deleted automatically when deleting the profile.