Here's where the hidden stuff and histories actually live and how to clear them properly:
Browser data (usually the bulk of it):

Chrome/Edge/Firefox → Ctrl+Shift+Del → choose history, cookies, cached files, and the time range. This is where those hidden .dat-type files mostly belong — browser caches and profile data in AppData.

Windows' own histories:

Activity history: Settings → Privacy & security → Activity history → clear.
Recent files/jump lists: Settings → Personalization → Start → turn off "Show recently opened items", and clear File Explorer history: File Explorer → ⋯ → Options → General tab → Clear button next to Privacy.
Search history: Settings → Privacy & security → Search permissions → clear device search history.
Run dialog & typed paths live in the registry (that's NTUSER.DAT's job — this is why you never delete the file itself; the histories inside it are cleared via the settings above).

Temp and leftover files:

Settings → System → Storage → Temporary files → tick the categories → Remove. This safely covers the Temp-folder .dat files, thumbnail caches, delivery optimization files, old update leftovers.
Or the classic: Win+R → cleanmgr → select drive → "Clean up system files" for the deeper options.

Seeing hidden files generally: File Explorer → View → Show → Hidden items. Fine for looking — but the rule from my last message stands: hidden files in AppData, ProgramData, and the profile root (NTUSER.DAT and friends) are hidden because programs depend on them. Delete by category through the tools above, not by hand-picking mysterious files.
One question that shapes the advice: is this about privacy (removing traces of activity — from other users of the PC? before selling it?) or about space? If it's "preparing the PC to sell or pass on," the right answer is different and more thorough — a full Reset with the "clean data" option. Tell me the goal and I'll point at the right depth of cleanup.