• Open SharePoint portal
• Navigate to Site Action > Edit page
• Add a new Content Editor webpart.
• In the Web Part Click on The option Click here to Add New Content, And on the ribbon HTML > Edit HTML Source Then Paste the below CSS Code.

<style>
#s4-leftpanel
{
display:none
}
.s4-ca{
margin-left:0px
}
</style>

• Save the Page. The Quick Launch section should not be visible now.
• Edit the Just added Content Editor web Part and Under Layout Section Tick the Hidden Check box and Click OK, Which will hide the Webpart from Normal View.