Old files from 3.x

[Egorkin]

I have from previous versions of the forum were the directories and files, which in my opinion is not needed.
Here is their list:

cache
hooks
interface
ips_kernel
lofiversion
public
404error.php
constants.php
dav.php
initdata.php

Can you delete everything already? Current version 4.4.6.

[Martin A.]

404error.php and constants.php are still valid files in IPS4.

If you use friendly URLs, 404error.php is a custom 404 error page used in your .htaccess file.
constants.php is a file used to store "advanced" configuration, such as cache/datastore storage method. 

[Egorkin]

Thank you! 🧑

[bfarber]

It is possible you may have some older content pointing to URLs in the public/ folder (particularly emoticons) so be careful removing that as well.

Otherwise everything else can go (besides what Martin already pointed out)