I think you should go on Google and ask:

1. How do I uninstall a software that I don't need on MacBook Pro?
2. How do I work Quick Time on MacBook Pro?
3 How do I delete Quick Time on MacBook Pro?
4. Why does i say 'Missing Plug-In. (Error-X-Object)

I think the answer for question four is hat you are trying to see media and you have not installed something that you must install in order to see media.

Hope I helped!

After you solve these three issues, READ some guides, links below.

1. Drag it to the trash. [[For reasons of technical wrong direction, Windows still uses a registry database which often does not allow you to simply trash an app. This means Windows users look for an "Add/Remove" thing in OS X, but there isn't any need for one. OS X and Linux don't have that registry yoke.]] Also, if it was added by running an installer (as opposed to just one "CoolApp.app" file dragged to the Applications folder), you should look in:
/Library /Application Support
for a folder related to that app. If the developer were playing by the rules, his support folder would be called "CoolApp", but sometimes they like to be clever and give their support folder some odd name that makes it in disguise. Example: Live Interior 3D uses a folder called "BeLight Software", and Firefox uses a folder called "Mozilla". When you find a support folder for the hated app, drag the support folder to the trash as well. Typically, there will be a preferences file, too. The typical format for an OS X preference file is "com.CoolApp.plist" but like the support folder, it can be oddly named as well. Luckily, prefs files are tiny, so don't spend hours looking for it. {{You can also use a remover app, but they sometimes don't do a complete job. I never use one, since they could also make a mistake of removing something I don't want removed.
(TrashMe, free) (AppZapper, US$13) (AppCleaner, free) (AppDelete, US$7.99) (AppTrap, free) (DesInstaller, free)
All too rarely, the developer designs an uninstaller app to go with his installer app. MS Office always has this uninstaller... thank the gods, since it puts files all over creation when it installs.

2. No one knows what you mean. Instead of giving us your opinion of what you see, tell us precisely what you see. Example: "When I double-click the QuickTime Player.app, nothing happens," or "...the Q icon in the Dock bounces twice, and then stops with no glow indicator below it," or "...I get an error message that says 'The file ___ is missing'". For the "does not delete" thing, hmmm... can't imagine what you mean. Delete means something should go to the trash. What is your idea of delete? BTW, you don't get any window on the screen just because you open QuickTime Player.app. Unlike Windows apps, many OS X apps can have or not have a window open at any given moment. To see a window in QuickTime Player.app, go to File > Open, and select a song or movie file.

3. Which page shows this "Missing plugin" message? OK, bunches, fine. But please name at least two. The standard plugins for web pages are QuickTime and Flash. Your system has both of them as it is installed by Apple, so don't fret those two. There are three or four odd plugins that require your installing something, but no way to tell you which one you need to install until you tell us which webpage address shows the message.