Can I remove my dental crown a second time if I am unhappy with the color?

It is very difficult to match a single front tooth as others have mentioned. Are you happy with the other five crowns? If you are, you can typically go to the lab for custom shade matching on that single crown. Your dentist should fix it until you're happy. When you make an appointment, make sure they schedule enough time by saying you're making the appointment to two the crown. When it comes to the delivery appointment, I'd recommend viewing the crown in different lights. You could even go home with it temporarily cemented to see if you, your family and your friends like it. If that's not an option, being them with you to the delivery appointment! 

Yes you can remove it a second time and replace it. A bit of advice for the next time, be sure
that the color is acceptable prior to final cementation. If you have a translucent crown such as E-max,
the color of the teeth underneath will affect the final shade (color), the
color of the cement affects the final shade as well. A crown with a Zirconia base will block out
the color of the tooth so the shade of the crown will remain the same
regardless of what’s underneath. During
the try-in phase, make sure the dentist uses a try-in paste the same color as
the cement to be used, this is especially true if the crown is E-max, which I
prefer for strength or some other translucent crown such as Empress. Persist,
you deserve to be happy with your smile.

You should voice your concern and get it redone  if you don't like. After all, this is your smile and you should be happy with it. However  it would be wise for you to inform your doctor at the crown try-in rather than after it is cemented. We usually do a try in with a variety of cement shade to make sure everything matches prior to cement. At the end, your dentist would want you to be completely happy with your smile.

Yes you can have the crown removed again but it will be challenging to match a single tooth. The dentist should have taken into account the fact that the base color of some of the teeth were different. Before permanently cementing this next crown spend time evaluating the restoration. Look at it in different lighting conditions. Possibly walk outside into the sunlight. If you aren't happy the dentist can work on the color, if it's permanently cemented there is no way to fix the tooth.

While it CAN be done, it is not easy and usually requires great communication with the lab from the dentist and great photography. One of the hardest things to do is a single front tooth?