As a general rule, you can not sell shares that have been delisted from the ASX. You certainly can not sell them on the ASX. There are rare occasions where the shares might become listed elsewhere (like on the NSX for example) or there may be offers made off-market to buy delisted shares, but not often. When a company is fully taken over by another company, as in this case (HCL taking over DWS), then the acquiring company (HCL Technologies in this case) own ALL of the shares, and you no longer own any shares. However, they paid for those shares, one way or another, so you need to find out where that money - or that cheque - went.
There are occasions where a company will issue you with shares instead of cash, or a combination of shares and cash, but that does NOT usually happen when the acquiring company is listed overseas, such as in this case (HCL is listed on the Bombay Stock Exchange [BSE] in Mumbai, India, under the code 532281 and on the National Stock Exchange of India [NSE] under the code HCLTECH), because most people would object to having ASX-listed shares exchanged for shares listed on an overseas exchange, and there are regulatory issues also if that was to occur, particularly when the acquirer is a US-listed company (HCL are not US-listed). So, generally, when an overseas-listed company acquires an ASX-listed company, the consideration is almost always cash, in Australian dollars. Hope that helps.