Can't find plugin menu version 2.5.1

I wish to upgrade a version 2.5.1 www.remarpro.com site to the newest version but in order to do so I first need to deactivate all plugins. Unfortunately I can’t find anything in the admin area for plugins, themes, etc. Only Write, Manage, Comments and Profile links are available. The goal is to migrate this blog to a different server. I can’t export anything from the old to the new because I can’t access the plugins. I’ve seen a number of similar postings but no solutions offered. Help!