Hi Albert-
That line is built into the Theme CSS for venetian, but it’s not tough to remove. Navigate to Customize > Advanced > Custom JS & CSS and add this line into your Custom Theme CSS field:
palette-primary .call-to-action h2 { border-bottom: none }
I’m glad to hear about the good GTMetrix Score, but I am sorry to hear about the PageSpeed Insights score. Can you share some of the recommendations it’s making so we can help you out specifically? Most of the time you’ll be able to improve that score with W3 Total Cache.