WHAT IS A MOBILE PHONE
As we all know that mobile phone is actually a device that we can use for multitasking like run social media,Camera,record videos,capture photos etc in our life. Generally mobile phones is easy to use or it is friendly with us and it is easy to carry as it's comfortable size in market there we can find any mobile phone according to our need and every mobile phone can have a different price point as an example we can say that as much specification as much price but recently it was studied that many companies tried to gave best mobile features in low price point because of mobile companies compition in today's life
WHAT IS PRE INSTALLED APPLICATIONS?
The application which is not installed by users directly they was installed by companies for make users easy to access users some of that application is can't be deleted because they have to operate that specific service you can exchange that service with another third party app but it is not 100 percent secure and by this you can not delete the main pre installed application but you can delete it by root your device.
SHORT REVIEW OF ROOT MOBILE?
In short we can say that by boot your mobile you can access or control your mobile fully before root or you can not control your device fully if your device is unrooted or not access to root. 

WHY SMARTPHONES HAVE MANY PRE INSTALLED APPLICATIONS?
As we all know that when a company design or launch a new phone there first priority is that to impress audiance and as these pre installed apps help us so companies main focus is to give users all services as they can provide on that specific price point and one more reason also can be that they not want that user use third party applications for access that specific service which can also in secure users data or may also slowed down the system process speed that can make user in comfortable.
IN SHORT HOW TO REMOVE PRE INSTALLED APPLICATIONS
To remove or uninstall pre installed applications you have to root your device this work can be done by any computer professional worker after root your device is to fully changeable.