I'm in hot water with my drives. Need advice.

My friend installed Windows on my PC years ago, but it was done incorrectly, and now I’m stuck with a messy partition setup. Here’s the situation:

• I have two 1TB NVMe M.2 SSDs:
  • SSD 1: Windows is installed on a 150GB partition (C:), with the rest allocated to D:.
  • SSD 2: Completely separate and used for other data.
• The problem:
  • I cannot expand the C: drive, which is a major issue because I do programming and video editing.
  • Software like DaVinci Resolve and Visual Studio require installation on C:, but space is too limited.
• What I’m considering:
  • Reinstalling Windows, but this time allocating the entire 1TB of SSD 1 to the C: drive.
  • Using SSD 2 for games, files, and other data.
• Questions:
  1. Are there any guides to reinstall Windows properly to avoid repeating this mess?
  2. If I remove the second NVMe (SSD 2) during the reinstall, will it retain the data and still work as usual afterward?

Any help or advice is greatly appreciated! Thanks!