Can Replay be disabled in Wireshark?

Assuming you mean you want Wireshark to make a capture file non-replayable by a third party, I don't think there's a feature for that. If your pcap contains src and dst IPs, it can be replayed, so you simply need to anonymize your pcap to prevent replay to the actual endpoints (the anonymization rewrites the IPs). You can do that with a variety of packet-rewrite tools, including bittwiste or tcprewrite. For tcprewrite, see Randomizing IP addresses.

I can think of two mechanisms to prevent replaying VoIP/VTC, filtering and slicing.

• Filtering. You can create a capture filter that will not capture VoIP/VTC traffic, but will capture all the rest for your intrusion analysis. However, it might be difficult to achieve this when random ports are used.
• Slicing. You can slice off the RTP data by setting a snap length. You might want to try 96 which will keep the Ethernet, IP, TCP and UDP layer and a few bytes of payload, so reconstructing a VoIP or VTC call will not be possible anymore. However, you might also lose the information that you are after.

The best way to deal with this is to capture all traffic and make sure that only certain people are able to access the capture files. There will need to be trust in those people that the files will not be used for replaying. You can then discuss some procedures on how to access, filter and delete the data.

Wireshark doesn't have a "replay" (send packets from a capture file to the network) capability.

Please explain in a bit more detail what you are trying to disable.