Can I leave my bags at your office while I am out on a tour?

No, unfortunately we are not allowed (by order of the local authorities) to store  luggage or bags at our offices in La Paz.
For most of the multiple day tours that we offer, you will be able to leave your big bags at the operator's office and collect them when you return. If you are not on a tour and just want to be able to walk around , then you should ask your hotel if they can store your luggage there as most are happy to do that free of charge. If you have  just landed/arrived and therefore you didn't stay in any accommodation the night before, you can still ask some of the hotels in the centre of the city/town you are in as some of them offer that service for a small charge.