If you are looking for Task Manager for Ubuntu, just like in Windows, where you can remove the unwanted applications or programs from the system, then this might be a helpful post.
Remove Unwanted Applications Ubuntu
Like Task Manager in Windows, Ubuntu provides System Monitor, which can help you removing the unwanted applications running in your Ubuntu.
How To Use System Monitor (Task Manager) Ubuntu
To open the System Monitor (Task Manager) in Ubuntu, goto:
System -> Administration -> System Monitor
A System Monitor window will pop up, there choose the Processes tab, and you will see the applications list running in your system.
Simply select the application or program you want to remove from the system, and right click on it. You will find several options on right clicking on the programs, where you can Kill, Stop or End the Process as per your requirements.
To uninstall or remove applications in Ubuntu, please check the following post:
Uninstall / Remove Applications Ubuntu