Reading further, the pricing appears to be calculated as `price = write_per_sec_at_95_percentile * num_datapoints`. So, despite the storage of data is free and the new datapoints don't as many write, the pricing will still be the top write_per_sec from the other part. Plus the addition of the new datapoints, the cost would increase drastically.
So, it appears not to be a good idea to implement in this way as for higher cost.
I guess this is a pretty late response - sorry .
No, there is no way to manually delete metrics.
The pricing is dependent on points per second. If you're sending 2000 points per day, that works out to 2000/(24*60*60) = .02 PPS (points per second), which is pretty low.