Marketpress store url slug reset

Hi,

I was playing with the store URL slugs under Marketpress>>Store settings>>presentation.

I wanted to redirect my store page to my homepage. Without giving it too much thought, I blanked the name of the store URL thinking it might be a clean solution. Needless to say I want to switch back and do a redirect instead and I am getting an error: 'Store base URL conflicts with another page'.

How can I reset this back to default?