db = db.getSiblingDB("test");
db.getSiblingDB("admin").runCommand({ shardCollection: "test.weather", timeseries: { timeField: "timestamp", metaField: "metadata" }, key: {timestamp: 1} });
db.system.buckets.weather.drop()

The above fails with this error in v6.0.9:

MongoServerError: drop collection of a sharded time-series collection is not supported

This error is misleading; it seems quite possible to drop a sharded time-series collection, but it has to be done on the logical collection (i.e., the view) rather than the buckets.

Suggested revision:

Drop on a sharded time-series system.buckets collection is unsupported; drop the view instead.