If you like a welcome page of portal or selected pages without Quick Launch and the Tree View navigation then the easiest way is to implement the solution is to use the content editor web.
This solution is called micro solution which do not need code and uses content editor to insert style code embeded on the pages. Follow steps below to implement solution.
Step 1. Open Page in edit mode where you do not need Quick Launch Menu
Step 2. Click on "Insert" --> Web Part to insert new web part on the page and select Content Editor web Part from "Media and Content" category on the page
Step 3. Add following text in the HTML Source mode
<style>
/*--Hide Quick Launch --*/
#s4-leftpanel{
display:none
}
.s4-ca{
margin-left:0px
}
</style>
Step 4. Save Changes and Browse the page.
