Go to Settings → System → Storage
Click Temporary files
Select:
Windows Update Cleanup
Previous Windows installation (if present — this is often 10–20 GB!)
Click Remove files
Open Disk Cleanup
Right-click → Run as administrator
Select your C: drive
Click Clean up system files
Tick:
Windows Update Cleanup
Delivery Optimization Files
Temporary files
OK → Delete
Go to Settings → Windows Update
Click Pause updates (for 1–5 weeks)