You probably have inherited this PIX from someone who has left your company and left no documentation. So before removing a conduit from config, check the conduit hosts src/dst/protocole and ensure it's useless. Dont forget some conduits may have not been requested since pix last reload or modification so hitcount has been resetted. Also you may have indication on PIX syslog's of the usage from this conduit.
Mixed ACL and conduit are not supported by the PIX.
There's a link that may help you for the convertion of conduit to ACL if you have CCO account:
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...