How to properly uninstall windows 7 and ubuntu 15.04?

Question

linux

Windows 7 and ubuntu 15.04 are installed on the computer, at startup I choose which OS to run. I completely decided now to remove windows 7 and ubuntu 15.04 and install pure ubuntu 16.04 on the computer. But the question was, how to remove all this correctly? There are 2 partitions drive C where the windows 7 OS is located and D where my files are.

Answer 1

Format partitions with unnecessary OSes.
But not with data.
The installer for the new operating system will prompt you to format. You just need to choose - and what exactly.

Answer 2

Delete disk partitions from windows 7, ubuntu 15.04 and create new partitions to your liking.

Answer 3

The Ubuntu installer contains advanced partitioning tools. At the stage "Installation type"*, you need to select the "Other option"* item, this will allow you to delete and create the necessary partitions. You can boot Ubuntu not immediately into installation mode, but into trial mode to see which partition is which (where is the data and where is the system, you can match them by numbers, by labels, by size, free space), i.e. protect yourself from deleting the desired partition.
* - I did not install it on 16.04, the names of the items may differ.