1. Microsoft Learn | Power Platform ALM Guide: "Update or upgrade a solution". This document explicitly contrasts the two actions. It states, "The upgrade option deletes any components that existed in the previous version but are no longer present in the upgraded version." This directly supports the choice of 'Upgrade' for removing obsolete components.
Section: "Import the solution" > "Upgrade" option details.
2. Microsoft Learn | Power Platform ALM Guide: "Solution concepts". This guide details the behavior of different solution operations.
Section: "Solution layers" and "Importing solutions". It explains that an upgrade consolidates all patches and the base solution into a new version, replacing the old one and its related patches.
3. Microsoft Learn | Power Platform ALM Guide: "Create and use patches". This document describes the patching process and its lifecycle.
Section: "Clone a solution". It clarifies that after creating patches, you use "Clone Solution" to merge the changes into a new version of the parent solution, which is then typically deployed using the Upgrade option. This shows that patching is a preceding step, but the upgrade is the action that fulfills the question's requirements.