Unfortunately this forum is for product support.
There are better forums for questions like yours like baby pips or
http://forum.mql4.com/Next time, If you have a question about metatrader basic usage please post it there.
When asking make sure do not use "live market" because it sound like trading in a real account. Use the terms demo and real account so people will understand you.
As per your question, to attach the ea you drag and drop it into the charts. To remove it you can:
-Close the chart
-Right click on the chart, select Expert Advisors and then remove it