Am I able to turn off AirDrop on my iPhone?

To turn it off, simply swipe up to display your Control Center (that menu at the bottom of the screen where you can put the phone in airplane mode or access the calculator) and then tap on Airdrop. Tap Off to disable the feature

Go to Settings - General - Airdrop - Receiving off

a quicker way for the future:

If you have an iPhone X, Xr, Xs or Xs Max, then swipe down from the top right hand corner of the screen to access the control centre. From there 3D Touch (push hard on the screen) on the aeroplane. Click ‘Airdrop’ then click ‘receiving off’

if you have an iPhone below the X models, swipe up from the bottom of the screen then follow the same instructions.

Why? It's a very convenient way of sharing photos and other stuff. You can not use it if you wish.

Use AirDrop on your iPhone, iPad, or iPod touch - Apple Support