If your casual or doing a traineeship Im sure you can ring them and just fax the letter of resignation so you dont have to see them.
I worked at this shithole helpdesk for pharmacies for 4 weeks and couldnt heck it, so I rang em and told them I wish to quit, they asked me to bring them a formal letter with my resignation, I asked if I can fax it... went to my old employer (got my old job back which I loved) and faxed it from there
If you have been with a company for a long time and have a perm pos then its diff.