Once you’ve placed your request to unpledge , and we’ve accepted it, the unpledged shares will reflect in your only on the next trading day (T+1). You can then sell your unpledged shares on the following trading day (T+2). 

Let’s understand this with an example. On Monday, you submit a request to pledge 100 shares. On Tuesday, you will receive the relevant collateral margin in your account for the pledged shares. On Tuesday itself, you can place a request to unpledge these shares. However, you will be able to sell these unpledged shares only on Wednesday.