"Quote Template" is a field you select when you create an opportunity. The Quote Template field serves as a way to define common elements that are required for opportunities of the same nature.
You can add as many quote templates as you need under "Settings > Opportunity > Quote Templates."
For each quote template, you can specify the following:
Payment terms
Proposal template
Items
Labor types
The following screenshot is a typical example of a quote template.
When you select a quote template for an opportunity, the product, labor, and payment terms come pre-loaded in the quotes of that opportunity. This reduces the effort and time to build quotes.
If you want to remove or change the default items pre-loaded from the template, you can do so with the item addition, updation, and deletion options in the quote.
If you want to remove or change the labor types or change the payment terms, go to the Quote Details view, the 3-dot menu of the quote, "Settings > Payment Terms," and make the changes.
If you want to change the proposal template, change it in the Edit Proposal view.