Switch a Multsite Subdomain Install to Directory Install

Is this possible?

Our network has approx 15 sites on it.
Limited content ( not live yet) , but design, plugin and functionality-wise we'd want to keep things preserved.

We're looking to switch over to a directory install primarily to consolidate branding under a single domain and to also only manage a single ssl certificate instead of multiple (1 per subdomain).

Any help is much appreciated. thanks

Paul