How do I fix this reverse taper?

[Noulinator]

I have to ask. Do you want to get rid of the reverse taper because "a tree should not have reverse taper" or do you really not like the look of reverse taper? If you really don't like the look of it, then you should try to get rid of it. I think it's a great tree with its own personality. Maybe enjoy it for what it is and get a "good" tree later on.

It’s just mostly a project tree and I am new in bonsai. So I would like to try to improve this tree as much as possible as a fun project and an opportunity to learn and try out different techniques.

I just ordered the maple bonsai book by Andrea Meriggioli yesterday.

 

[Noulinator]

I

Which area of reverse taper are you referring to? The pictures appear to show several. If referring to the lowest section near the base, I would consider that a smaller issue than the others or the straighter section with less taper above the initial lower movement in the trunk.
The important aspect os how much work are you prepared to do and how much improvement are you wanting to make with this material? What are your goals?

It was the one near the base.
The rest I would like to try and cut off / remove by tools

My goals with the tree is it being a project tree. I would like to try different methods on it as I am new in bonsai and need practice. So I am prepared to do a lot and would be fun to see what I can make from it.

 

[River's Edge]

I

It was the one near the base.
The rest I would like to try and cut off / remove by tools

My goals with the tree is it being a project tree. I would like to try different methods on it as I am new in bonsai and need practice. So I am prepared to do a lot and would be fun to see what I can make from it.

Patience will be the key. Do the work at the right time and space it out so the tree does not have to try and heal everything at once. When you get merrigioli's book note that the improvements you are wishing to make are done so over several sequential steps, not one cut or graft. Quality results take time and a lot of preparation to bring the tree up to a vigorous level and maintain it over an extended period of time.
Projects like this can be very rewarding and super learning experiences for technique. They also are very instructive moving forward in selecting and developing material. No substitute for experience.
When making the changes keep the three major artistic principles of Bonsai design in mind. Strive for proper proportions, balance throughout and a sense of Unity.
The basic trunkline informs you for the overall direction of design. The degree of initial movement directs the amount and type of movement throughout the design. Study the change in direction, thickness and taper throughout the trunk, primary and secondary branching etc.
When taking the time to make improvements the most important factor is deciding how far back one should start with the existing structure.
Ask yourself what will the section look like after the change?
For this tree the key area for me would be the main mid section of the trunk. If thicker sections were trimmed away would the movement improve ?
Sometimes it may be best to retain character. Would that main section become more congruent with the bottom or top section or less so. What combination of changes would be most effective to enhance, proportion, balance and unity.
Of course these questions are all separate from simply using the material to practise formation techniques. It involves combining a learning experience with the goal of making the most out of the material.
Whatever you choose to do, enjoy the experience.
Best in Bonsai