There's an easy way if you’re an administrator or a proof manager and want to disconnect a version from a proof set. Open the Proof Details page, select the proof version you wish to disconnect, and click on the “Disconnect version” button under the contextual menu.

If you need to replace a proof version with another one, use the Move version action. To do this, please open the Proof Details page. Click on the “Move version” option located under the contextual menu. Next, select which proof from the list will be placed before the version that you are currently on.

The selected version will become a proof version before the version that was opened in Proof Details mode.
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FAQ: How do I delete a proof version in the middle of a proof?​