Be very careful. That is a brand new, unused sprocket, very hard to come by. The smaller, Dynamo sprocket looks in good shape also.
Removal is effortless. The crankshaft has the standard Villiers 1-10 taper. Removal demands the standard technique for any taper. Attach puller, tighten up very tight then a smart blow on the end of the puller to pop the taper.
Any competent mechanic can demonstrate the technique to you.
Get yourself a decent puller set. Do not spoil what you have through want of good tools.
Good luck