Go to your Joomla! 1.5 Administration (Backend) eg. www.yoursite.com/administrator and login with your username and password
Click on Menu -> Main Menu and select the Home page link
On the left hand side you’ll see the Parameters Options. Select Parameters – System on the Left Hand Side and next to Page Title you’ll see stands “Welcome to the Frontpage”. Remove it and enter custom text. Or if you don’t want any text to be displayed on Home Page simply select Parameters – Component and set Show Article Title to No.