renp

A simple WordPress plugin which adds a “scroll to top” button to the bottom corner of the page if the page has been scrolled down. It is compatible with all major browsers and should work with all themes, including 
responsive and high resolution themes.
It is possible to configure the plugin in the admin area for choosing between light or dark colour schemes and size of the button as well.
If your theme doesn’t already contain this feature, you can simply add it by means of this plugin.

Scroll to Top Button

Displays a button in the bottom right corner for smooth scrolling to the top of the page.

wpforest

Simple Scroll Up Button Plugin adds a floating scroll up button at the bottom right side of the page when scrolled down. When clicked the button, rolls smoothly to the top. This is convenient when you have a long page, and you want to give your visitors an easy way to get back to the top.
When visitors have to scroll down to read the content on a long page or long post, they need to scroll up to see what else is there on your website. Scrolling by their hand with a mouse or trackpad to the top is very tedious. Simple Scroll Up Button Plugin helps to reach the top by one click. Also, the transition is smooth and improves user experience. You can choose the color of button to suit on your website.

Simple Scroll Up Button

Simple Scroll Up Button is a lightweight plugin which adds a simple scroll up button on the page of your WordPress website.

Scroll to Top Button vs Simple Scroll Up Button