Title tag
Does your theme come with a support service you could ask.
You may be able to change the tile using the wp_title hook:
https://developer.ww.wp.xz.cn/reference/hooks/wp_title/
ww.wp.xz.cn members don’t have access to your theme’s code, so it would be difficult to advise and debug full code lines to do this.
Yoast SEO plugin > Titles and Metas menu item allows you to control the title tag.
There are some other plugins you could try, though they look fairly new:
https://ww.wp.xz.cn/plugins/title-tag-everts-simple-version/
https://ww.wp.xz.cn/plugins/mypace-custom-title-tag/
Breadcrumb
You can use this custom css to hide the breadcrumb:
.breadcrumb {display:none}
If your theme does not have a setting where you can enter custom css, you can use a plugin like this one:
https://ww.wp.xz.cn/plugins/simple-custom-css/
