>>18271
You can select these particular elements you want to hide with the :nth-child(x) selector, where the x is the number of the element.
The elements of the form is in the table and the "Password" and "Drawing" fields are in the 5th and 6th table rows, or in the 4th and 5th if you force anonymity via your board's settings (ie. no "Name" field).
Then you can use display: none; css rule to hide elements (there are other options, if you prefer something else you can use that ofc);
Since no other table rows on the page you could use the following:

tr:nth-child(4), tr:nth-child(5) {
  display: none;
}

Or:

tr:nth-child(5), tr:nth-child(6) {
  display: none;
}

Depending on the Name field, as I wrote above. This is important, you don't want to hide captcha accidentally or something.