Before I opened up this topic, I used the searchtool. Followed these steps:

- https://themenectar.ticksy.com//ticket/1099600/
- https://themenectar.ticksy.com/article/2221

It worked for almost everything I wanted to change. The only thing I can't make invisible is the author within the post (see attachment). 

Current CSS code:

/* For Blog page */
body .meta-author {
    display: none !important;
}
body .meta-category {
    display: none !important;
}
body .meta-comment-count {
    display: none !important;
}
/* For Blog Single Pages */
body #single-below-header {
    display: none !important;
}
/* hide date and love on masonry blog */
body #post-area.masonry article.post .post-meta {
    display: none!important;
}
article.post .content-inner {
    border-bottom: none;
}

.single-post #page-header-bg .section-title {
    visibility: hidden !important;
}

I only need to know what the CSS code will be like, to remove the author en meta for the category page (each category). Just like this one:

https://www.ciz2.jumprocket.nl/category/agenda/

The other points are already solved. Ofcourse. I tried a lot already.

Thank you Tahir. We're there almostly. I tried the following extra line:

.masonry.material .masonry-blog-item .entire-meta-link .blog-recent .entire-meta-link {
    display: none !important;
}

To remove the author in this situation: (the recommendations)
https://www.ciz2.jumprocket.nl/michael-wilmering-ahmad-joudeh/

I'm only a designer. CSS is not my strongest point yet ;-)

Thank you! I learning it a bit. Still a question mark in case of this situation:
(see attachment: how-to-remove-only-author-date-and-comments.jpg)

The current CSS code also removes the title on the single article pages. I already tried a lot to remove the right details. But everytime there appears a red cross in front of the box. 

The rest is absolutely fine. Thank for your great help.
The only thing I can't find to remove, is this situation:

We want to remove the date note in the Nectar Popular Posts widget
(see attachment: how-to-remove-date-nectar-poplar-posts.jpg)

By the way a big thanks from Holland! Normally I would ask the developer on this case, but he is off the case right now because of big delays. I'm just a designer who loves to build websites with Salient and kinda help them out of the fire.