The initial information on the existence and location of the collection you are looking for is to be found in the Czech Archival Collections Database of the Czech Ministry of Interior. The necessary addresses and contacts of the Archives in the Czech Republic are to be found e.g. in the directory of the Czech Archive Society.
archival collections produced by entities (authorities, institutions, companies, schools and other legal entities and individuals) active on the territory of the City of Prague. These are namely:
Catalogue - a database of collections, holdings and electronic aids of the Prague City Archives