You have two options for removing it.
1. Edit the post or page and enter the HTML editor and remove the font code. Publish.
2. Edit the page or post in the Visual editor. Select and copy and remove all the code for the whole post then click Icon 5 in Row 2. To display the second row of icons, select the kitchen sink icon A pop-up box appears. Paste all the code into it and click to insert it into the post. What is posted will eliminate all the bogus code and post only clean code for you. Publish.
See here > http://en.support.wordpress.com/visual-editor/#row-2
You may not like the fonts supplied your wordpress.com theme but it’s important to know that regardless which fonts you may wish to choose to jazz up your blog with, your browser and your visitors’ browsers can only use the fonts installed in the same computer. Obviously not every visitor to your blog will have the same fonts installed in their computers as you do on yours, so you can immediately see that problems will arise unless you choose to use common fonts.
If a reader does not have a specific font installed on his / her computer, the browser will determine which font is displayed. There are a very limited number of fonts (in English/Western languages) which are common for most operating systems/computers/browsers. > http://onecoolsitebloggingtips.com/2010/02/04/changing-fonts-in-wordpress-com-blogs/