This can easily be accomplished by adding an Content Editor Web Part to your SharePoint page. Edit the Web Part and choose: HTML > Edit HTML Source > Paste the following style
<style type=”text/css”>
.v4master #s4-leftpanel {
DISPLAY: none
}
.v4master .s4-ca {
MARGIN-LEFT: 0px
}
.v4master #s4-leftpanel {
DISPLAY: none
}
.v4master .s4-ca {
MARGIN-LEFT: 0px
}
And click save.
For changes on a bigger scale you can add the style between the <head></head> tags of your masterpage.