How do I stop a webhook for a while without deleting it?

Pause it.

1. Go to Plugins → Webhooks.
2. Under Subscriptions, find the webhook and click Pause. Its badge changes from active to paused.
3. When you are ready, click Resume.

While it is paused:

• Events that happen are not sent to it, and they are not saved up to send later.
• Deliveries that had already failed and were waiting to retry stay on hold, and pick up again after you click Resume.

If the new server has a different address, it is better to create a new webhook for that address and then delete the old one, since the address of a webhook cannot be changed.