congratulations on your 17 r2.

about the battery, the answer is no, you don't need to remove the battery from the laptop, even if the laptop is connected to the adapter all the times (to me it's a good protection to power loss). since a few years ago, laptops already have a smart mechanism that prevents battery from recharging too frequently. when it's still above certain limit (i think it's about 90% or more) it will not charge. the charging only gets triggered when the battery is below that threshold.. furthermore, if you right-click on the power icon at the notification area, dell has a battery protection option that you can set up to help reducing recharging. it will cut off the power source, drain the battery, then to let it charge once in a while.

my m17x r4 is always connected to power adapter with battery installed. even after 3 years, my r4's battery wear level is still minimal.

however just bear in mind that battery is still wearable. it will wear more if you're on battery power most of the times.