Best I can suggest for protostar is to edit it and set the Advanced parameter "Fluid Layout" to "Fluid". Then use some custom CSS to remove the padding on .container-fluid or add a negative margin. Example as follows.
Code:
body.site.com_comprofiler.view-userprofile > .body > .container-fluid {
padding-left: 0;
padding-right: 0;
}
There's more padding on the body element it self, but if you remove that it'll look strange being completely edge to edge. Regardless is an example that should help get you started. If you're not familiar with CSS I recommend contacting a developer to help you (we do not provide coding assistance, just simple examples). It will likely be easier to find a template that gives better control over its layout though.