Is it possible to rename a macro without having to delete and start over?

Yes. Right mouse click on your macro listed in the Macro Explorer window. Left click on Properties from the menu that opens. Click on the Activation tab. Select the activation you want and either assign a new hot key or other type of activation.

You can also do the same thing from the Scripting Editor. Click on the Properties Tab and change activations or add another type of activation.

Both of these options will also allow you to change the macro nickname.