Hide Page Title Plugin Caused Huge Error on Site

Hi, I installed and activated a plugin to hide the Home Page title.

As soon as I installed it I got an error message. Now I can’t use the Preview for pages or posts. And, when I Update a page or post I get this message:

Warning: Declaration of pdc_walker::start_el(&$output, $page, $depth, $args, $current_page = 0) should be compatible with Walker_Page::start_el(&$output, $page, $depth = 0, $args = Array, $current_page = 0) in /home2/lindawi3/public_html/wp-content/plugins/pc-hide-pages/admin.php on line 92

Warning: Cannot modify header information – headers already sent by (output started at /home2/lindawi3/public_html/wp-content/plugins/pc-hide-pages/admin.php:92) in /home2/lindawi3/public_html/wp-admin/post.php on line 197

Warning: Cannot modify header information – headers already sent by (output started at /home2/lindawi3/public_html/wp-content/plugins/pc-hide-pages/admin.php:92) in /home2/lindawi3/public_html/wp-includes/pluggable.php on line 1210

I have to back out of the page to get to the previous page. It does update thought, thankfully.

I also have a banner error message across the top of every folder/file (Pages, Blog, Media Library, etc) in Dashboard (a screenshot is attached).

AND, when I use Internet Explorer or Google Chrome, I get a page with the same error message when using the https://lindawilsonauthor.com/wp-admin URL! I can’t get into the site with either browser.

So far, I can get in with FireFox.

I’m using the WriterBlog theme and updated the WP 4.8 again.
The URL is https://lindawilsonauthor.com

I’m not tech savvy. That being the case, can I fix this? If so, how. If not, is there anyone who can help?

I’m at a loss.
Thanks so much for your help,
Karen