It is possible to do this - but you must download the 4.0.1 image. You don't need to install 4.0.1, but the base image must be present. 4.0.x, where x is 4 in your case will then use the base image out of the 4.0.1 bundle to complete the upgrade.
Please also make sure you're on the latest content release (you can check the release notes for exaxt version required if needed).
Yes, you can do this as subsequesnt upgrades to 4.0.x branch will be maintenance releases only. Although there is no need to delete it.
Click Accept as Solution to acknowledge that the answer to your question has been provided.
The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!
These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the Live Community as a whole!
The Live Community thanks you for your participation!