This is going to depend on the specifics of your story, but a supernova happens when a star runs out of easily fused fuel (hydrogen, helium).

If you want to prevent the supernova entirely and return the star to "normal," that means removing all the heavy elements from a stellar core and adding lighter elements. I'm no scientist (or author), but turning back the clock like that is beyond my imagination.

Absorbing the energy for use in other applications? Any sufficiently advanced technology is indistinguishable from magic, so....maybe? You can probably hand wave that way. It won't be 100% efficient, and whatever tech that's absorbing that energy has to be able to contain a star. This one has at least some hypothetical support: https://en.wikipedia.org/wiki/Kardashev_scale

A Type III civilization is able to capture all the energy emitted by its galaxy, and every object within it, such as every star, black hole, etc.

It reminds me of the Ringworld novels. I won't rehash the entire plot, but basically an artificial structure is built that requires a material the author calls "scrith" that is essentially impossible with known physics, but a clever author can write around it well enough that it doesn't get too much attention for its "magic" properties.

The main reason why a star collapses is because it's taking more energy to fuse elements than it gets from the fusion, this happens around the time the star starts fusing iron. Absorbing more energy from the Star during that phase would actually exacerbate the problem. You would need to find a way to inject more energy into the core, but not so much that it would exceed the gravitational pressure and cause the star to rip itself apart. It would be like trying to balance a bowling ball on a pin during an earthquake until the fuel ran out. And the fuel would run out very fast.

It would take Godlike levels of technology and it's still unlikely to work, even with that level of tech.

/u/Chainweasel@lemmy.world explains this well, though I got a different take on the analogy.

Imagine you are trying to put air into a deflating balloon that's about to 'loose form' that's essentially what you are trying.

Put just enough air (energy/mass) into the star and it will stay stable, loosing as much as you put into it.

Too little and the star will dissolved, in this example you'd fully absorb it.

Too much and you are essentially infusing a star with so much mass that it explodes all over again.

If you are trying to stabilise a star this way, ideally, it would never even begin to go nova.

https://youtu.be/cw20VbX1XCc?si=OiZJV8VBsFjWQ4JC

A lot of people here have the right idea, but are just more pessimistic than me about the industrial capabilities of our civilization if we survive long enough to achieve them. Star lifting is an idea with what I understand to be reasonably sound scientific principles. It's just a matter of scaling our industry over the next millions or billions of years.

I like this channel because he's a fairly optimistic but very reality based futurist. He'll tell you straight up if something is unlikely or impossible based on our current understanding of science, but he's one of the few sources I've seen that acknowledges the immense scale that even an Earth or solar system bound civilization is capable of supporting with just modern technology.

A requirement for supernova is a star's total mass being above a certain threshold.

If you can imagine some way of siphoning off mass, you could do it.

One imaginable way would be to move the sun (entire system in tow) close to a black hole or larger sun or something to feed off it. This might well be a recipe for causing a bigger mess, but it might be believable. https://m.youtube.com/watch?v=v3y8AIEX_dU

Wormhole is also a scifi magic solution.

In short, no.

Preventing a supernova would require halting the gravitational collapse of the star as it runs out of fuel. This means either feeding the star faster than it can burn (our sun is too small to nova and still burns through 600 million tons of hydrogen per second), or removing the iron, silicon and other metals from the core of the star faster than they can build up (slightly fewer hundreds of millions of tons per second).

You're going to need some very unrealistic scifi to accomplish either of those. Either some mechanism for pulling gigatons per second from the bottom of the star's gravity well, a plentiful supply of gas giant planets you can drop into it, or both.