Thank you for using the ask a question service, courtesy of Android Forums! Unfortunately in order to answer this question we need to know what device you are referring to, as there are many devices out there and your question can be interpreted in many way. You can download a task killer application from the Play Store if you are trying to disable running programs, though I do not recommend them since Android is already very good at memory management.
Please resubmit your question and provide the following information and we will gladly help you!
-Device and carrier
-Are you trying to close all applications on a device, are you trying to close multiple tabs in a browser?
We look forward to you reposting!