I'd say go bankrupt and start again...
Couple of reasons, selling that 74k would improve your situation a bit yes, BUT tere is a salary floor you'll pay each week anyway. Which should be around 70-80k a week in your league. So there is no point going below that with salaries.
Your arena prices are wild. 15 for stands is way off chart.
You haven't touched your arena in 4 seasons, arena is most of your expected profit. And you should start developing it early.
Even if you manage not to go bankrupt by sales of players, your economy is in shambles at this point and to develop arena at this point, it will take ages.
If I were in this situation, I'd chose to go bankrupt, start over, develop economy first train / buy couple of cheap 10-15k players and that will be enough for 4th division.
Learn a bit about ticket prices from forums/youtube and start rocking
there is nothing wrong with going bankrupt, it happened to more ppl here then are willing to admit it
You wanted to go to 3rd league from scratch, which is nice but it's wrong end to start this game with.