I have money in VTI right now. Once I sell the shares and the trade is executed which should be immediate is there any way to take that back just for some unforeseen reason what I had in mind for it doesn't work out?
Nope.
Just buy it back immediately.
Since it is VTI and you presumably have had it for a while, you have capital gains. The wash sale rule does not apply to capital gains, only losses.
You pay taxes on the gains (taxes will range from 0% to your marginal rate).
Don't do that - unless you have a margin account, you might violate "SEC regulation T". I think it requires you to be out of settled cash - so that you're using the money from selling VTI to fund buying VTI later. If you do this rarely, it's just a warning... but your account will be frozen & locked the moment the trade executes, and you're done for the day. I think they review it manually and unlock it later.
https://www.investopedia.com/terms/r/regulationt.asp#special-considerations
I've made that mistake maybe 1-2 times a year, since Vanguard puts up warnings for almost every transaction. I tried getting in the habit of checking if my trades for a given asset have settled, and only then follow a sell with a buy. Since switching to a margin account, I no longer have that problem (the cash needed to fund purchases comes from a margin loan, not borrowed from cash that hasn't settled).
An easy way around that is after selling VTI, buy a very similar ETF like ITOT. Both have the same expense ratios and same number of stocks. I think trades take 2 days to settle, which means waiting 3 days. Then you can switch back (sell ITOT and buy VTI.. or do nothing, they're extremely similar).
The trade that causes the SEC violation is selling the stock that was purchased with the unsettled funds, not the purchase itself. It's Freeriding that isn't allowed in non-margin accounts. Investopedia provides this example:
Say you decide to sell shares of Boston Scientific (BSX) on Monday. You then use the cash from the sale to buy shares of Johnson & Johnson (JNJ) on Tuesday. You sell those JNJ shares on Wednesday, a full day before your sale of BSX shares settles.
Because settlement for the BSX transaction did not occur until Thursday (T+1), there was no cash to cover the purchase of JNJ on Tuesday and the sale of those shares on Wednesday. To avoid freeriding, the investor would have had to wait until settlement—Thursday—before offloading the JNJ shares.
So assuming OP has owned his VTI for a week, he can do the following:
Sell VTI at 2:20 pm
decide he shouldn't have sold
Buy VTI* at 2:25 pm
His broker should stop him from selling the VTI purchased at 2:25 until the cash from the sale at 2:20 arrives, in 2 days.
But he can't do the following:
Sell VTI at 2:20 pm
decide he shouldn't have sold
Buy VTI* at 2:25 pm
change his mind again
Sell VTI* at 2:30 pm
The sale at 2:30 would have violated regulation T.
*for simplicity I'm using VTI, but the restriction applies to selling any stock purchased with unsettled funds.