Why would the bank delete it? It's not in the transaction history that immigration gets. They get a bank statement that shows 800,000. That's all they care about after receiving their extra money to make sure that's all they care about.
If you're talking about inside of Thailand, with an application at immigration, then yes. It's a common practice used by agents to bypass the financial requirements of a retirement visa. They take you to the bank, transfer the required funds into your account, get the letter and bank statement from the bank, then transfer the money out of your account. It's only in there for a few minutes. And then because the bank letter/statement does not show the funds in your account the required amount of time, part of the money you pay to the agent is so the immigration officers look the other way about that.
The DTV will be the only one that will allow you work remotely legally. That's really not a huge concern for most people though.
I would say to see if you can qualify for the LTR Remote Worker visa. The LTR visas are some of the best in Thailand, but the remote worker one is pretty hard to qualify for. If you can qualify for that, you can add your husband as a dependent and then you'll both get the benefits.
Second option if you care about doing things by the book, would be you getting the DTV workcation visa. Then you can officially legally work in Thailand remotely. You could also get your husband a 5-year dependent DTV based on yours.
The other 2 options are you get the DTV and he gets a non-O retirement visa. Or you both get a non-O retirement visa and you just work on the downlow, which many people do.