Open File Explorer, then right click on the drive (C:) and select Properties from the pop-up menu.
In the Properties window that should appear, click on Disk Cleanup. When it finishes the first scan, look for the the option to clean up system files. When that scan finishes, look at the list of areas for cleaning, and tick or untick sections as you see as appropriate. Click OK and then confirm that you want the files deleting.
Windows 'knows' what is safe to delete.
If you need more space, then programs such as Ccleaner can be downloaded and installed. Be careful with the installer. Make sure you set any options in the download and install correctly or you may end up with junk software as well as Ccleaner being installed.
You can repeat Disk Cleanup on other drives if you have them, but apart from the recycle bin, other drives do not tend to accumulate as much junk.
Once you have removed the junk, if it is a Hard Disk Drive (HDD) and not a Solid State Device (SSD), then consider defragmenting the drive. Don't defragment and SSD. Instead, optimise SSDs, which should improve their write performance.
Run the tool "dfrgui.exe". This should correctly identify your drives as HDDs or SSDs and allow you to defragment the HDDs and optimise (trim) SSDs to get the best performance from your system. Only do this after removing the junk files.