As the others said, you must leave the table possibly being allowed to sit out and come back to your seat if your lucky. You even have to leave the table in online poker if you want to bank any of your winnings. The reason being is that the people who you won money from expect at least the chance to win it back while you are still at the table.
I use the bankroll management strategies that Jesus Ferguson used when he did the $0 to $10,000 challenge on full tilt, turning $0 into $10,000 in about a year and a half (the first 7 months going from 0 to $6.50 playing freerolls)
On leaving the table...
If at any time during a No-Limit or Pot-Limit cash-game session the
money on the table represented more than 10 percent of his total
bankroll, he had to leave the game when the blinds reached him
Bankroll strategies for buy-ins ...
Cash game or STT/SNG - Buy in must be 5 percent or less of total bankroll, or at lower limits, not more than $2.50.
MTT - Buy in must be 2 percent or less of total bankroll, or at lower limits, not more than $1.
You should never play in a game that is beyond your bankroll
simply because the game seems to be soft that day. It's never soft
enough to risk money that puts your bankroll in jeopardy.