Step 1:Go to Sharepoint site Homepage.
Step 2: SiteActions-->EditPage-->Add Webpart--->Select Content Editor Webpart from Miscellaneous section.
Step 3: Click on edit of now added CEWP and select modify shared webpart and select Source Editor section.
Step 4: Write the below script in Source Editor in
style tag

.ms-navframe
{
display:none;
}
Step:5 And say Apply then OK.