Hello, I’m new here, and a noob, how I can create subpages for my site? like, I want to create and remove

That depends on what you use to build your website. What do you use to build your website?

SiteBuilder of the control panel

You can edit the pages on your website in the site builder by clicking the menu, then click the pencil icon in the top right and then go to Edit Menu. There you’ll be able to add and remove pages.