It's only five minutes to the Sorell Head Office from the train station in Stadelhofen. Go along Mühlebachstrasse past the Commercio restaurant and continue straight on. Go across Kreuzstrasse and you will see Mühlebachstrasse 86 about 400 metres further on.
If you're taking tram 2/4, get off at the Feldeggstrasse stop, cross Seefeldstrasse and continue down the left side of Feldeggstrasse. At the roundabout, turn left into Mühlebachstrasse.