When your first create a new website, you don't always know which templates to choose, and in some cases, you find that the template you selected is too overwhelming. However, even after you've created a site, you can change the overall site template (you need to be a site owner to access and change Site Themes). Here's how:
I chose a template that has too much in it; I'm spending forever removing text, pictures, and gadgets.
If you like the color palette of a template, a smart way to use the templates is as a theme. That is, you can create a site with the blank template and then use the instructions here to use that template as the color palette/theme for your site.
I am worried that changing the template after I've created my site will remove/delete my own content.
Don't worry; adding a template as a theme as per the instructions here will not copy over you page content. It will only replace the colors, fonts, logos, and background images in your site.