Share ISA clarification

[kencom]

Could someone please clarify if the following is possible with a share ISA?

In the current tax year (£20k allowance)

1. Deposit £20k in S&S ISA
2. Invest in shares, which shoot up and double the pot.
3. Sell all the shares
3. Withdraw profit, of say £10k, with no income tax/cap gains tax implications etc
4. Re-invest the remaining £30k still within the shares ISA

I think this is how it work, but not 100% sure

[kencom]

Thanks