how can i delete an application in my mac computer

Check with the Developer of this Application(s) for the Specific Instruction(s) to remove their software.

The above will only apply to Third Party Software

If the user is referring to Applications which are built into the Operating System, like News, Podcasts, Music, TV etc - these Application can not be removed or deleted. - period. They can be removed from the Dock but will still be present in the Application folder.

Apple Applications like Pages, Number, Keynote, Garageband and iMove can be removed. In Applications folder >> Right click the icon and a sub-menu will present. Choose Remove

If you cannot find the delete function from the app then you can drag it to the trash or use the program "Appcleaner" to remove.

https://www.macupdate.com/app/mac/25276/appcleaner