exec dbo.sp_msforeachtable 'delete test.dbo.[?]'
There's generally no need to do a delete without criteria, as truncate will perform better with less logging:
exec dbo.sp_msforeachtable 'truncate table test.dbo.[?]'
That said, I'm sure it depends and there's a situation where the delete will be preferred for some reason, I just can't think of one in anything I've done.
Puto me cogitare, ergo puto me esse.
I think that I think, therefore I think that I am.