My husband and I just purchased a new home. The previous owners had glass doors along the side of the bath tub. We unscrewed the doors and removed them quite easily but uncovered a mess underneath! The entire edge of the tub along where the bottom of the doors was is covered in old grout. The pieces of grout are large, sharp, jagged chunks. How can we remove these without ruining the tub? Your help would be greatly appreciated!!! Thanks!