The spines on the back of stickleback are its defensive weapons, and removing the spines requires certain skills and precautions. Here's a simple method:

1. First, put the stickleback on a flat or chopping board. A wet cloth can be used to prevent stickleback from slipping.

2. Gently cut the skin on the back of the stickleback with a sharp knife or scissors. Be careful not to cut the flesh of the stinging fish.

3. Tear the back skin of the stickleback from the middle to both sides, and then gently pull out the thorns on the back of the stickleback with your fingers or pliers.

4. Start from the head of the stickleback and move to the tail gradually to remove all the spines.

Be careful all the time, don't let the stinging fish prick you. It is best to wear gloves or wrap your fingers with thick cloth to prevent stickleback from stabbing your hands.

It should be noted that the thorns on the back of stickleback are very sharp, so be careful when operating. If you are inexperienced or uncertain, you'd better leave this task to experienced people. In addition, the spines of stickleback can be regenerated, so even if they are pulled out, stickleback will grow new spines again.