How can i modify This file name?

So file name is usually in this format

[HD] Dubstep - Azion - Fire & Ice
[HD] Electro House - James Egbert - Exit Wounds feat. Nina Sung (Cappa Regime Remix)
[HD] Electro House - Stryv - Storm
[Nu Disco] - Televisor - Automagic [Monstercat Release]

I want to remove the [HD] or HD if it ever shows up in the first four characters of a song title.

Also, how can I delete the genre name from the file name and move it to the "genre" tag?

For example in
[HD] Dubstep - Azion - Fire & Ice

the genre is Dubstep

is there a way to set it so that if it sees "dubstep" or "electro house" or "Nu Disco" that it'll delete it and add it to the genre tag?

sorry if i'm being vague

You can remove [HD] from the filename with an action of the type "Replace" for _FILENAME
Enter as search string: [HD]
(add a blank as last letter)
Enter as replace string:
(leave that empty)

BUT: I would not use the filename as data storage but use the tags as source which delivers the data for the filename. You can easily rename your files with the function

OK, this means that you have filled all your tags with data.
And as you want to get the genre from the filename into GENRE, this probably has to happen first.
For this also use a function from the Convert menu:
if the filename [HD] Electro House - Stryv - Storm
is a typical pattern, enter as mask:

[HD] %genre% - %dummy%
Or if you want to get all of it:
[HD] %genre% - %artist% - %title%

A problem are those tracks that have the genre in square brackets. You have to treat them separately:
[%genre%] - %artist% - %title%
[%genre%] - %dummy%

As the convert functions have a preview, you can easily see the probable result.