The simple and easy way you can remove startup items, you can uninstall the apps which you are not going to use to make sure the Mac is not clogged with software’s which are not needed now. The most normal way to get this job done is by just moving the unneeded applications to the trash folder. Unlike Windows, where in all the software’s you install would come along with a Uninstall file which should be run in order to completely remove the whole software from your computer.
You need to Go to Mac Hard Disk > Applications Folder under which you will find all the installed Applications on which you need to right click on the Application you want to remove and click on the ‘move to thrash’ option. Next you will be asked by the Finder to login to your account for getting access to proceed to the next step.
Once this is done, the application is removed and you will be able to delete the shortcuts to it which you would have created by adding the application to the Dock and also to the desktop. Also you can then safely delete all the contents of your Thrash folder. There is no Remove & Uninstallation Utility offered by Apple, but you can try out different free and paid applications which are developed by different developers.