I am redirecting using .htaccess to always use www, always use HTTPS. At this point, can I remove the duplicate Google Search Console properties (non-www and http)?
Yes. Google even prefers it. Only submit the URL you prefer your site to be accessed with. If https://www.domain.tld - Submit only that one.
After receiving a notice from Google (2-3 years ago?), I had to reorganize all my domains with Google when I switched some domains to https and whether or not they used www.
In short, it has to do with directly connecting to your site without redirects.