Drive Failure (How to Replace)?

I have a Drobo FS with 4x 3TB drives installed.
One of the drives have supposedly failed and the box is flashing the red led on the suspect drive, but the other 3 are flashing green/yellow constantly.

Now trying to find information on how to actually replace safely is tricky, as Drobo just seem to state “replace the flashing red led one” but it doesnt state if I can do it while the yellow and green lights are flashing on the other drives.

As when you read other help it states “dont remove drives when yellow and green is flashing”

So what do I do, remove the red one while the others are doing data protection?

It states in the dashboard that its going to take 36 hours or more to do data protection.

Alternatively I guess I could put in a new drive into the 5th bay and let it do its thing then remove the red failed one as required I guess?

Thanks for any help.