Just as every person is allowed to open as many savings account as he likes, there are no restrictions of the number of Demat Accounts a person can have. Moreover you can transfer shares from one demat account to another (whether that other demat account is owned by you or not) by following the steps.
- Fill in a transfer-shares slip. Every Depository (DP) usually sends out such transfer slips once in a year or so (just like banks issue check books). If you have not recieved them, contact your DP.
- Once you fill in the transfer slip, the shares will be transferred according to your given instructions within a few days.
- Click on Demat Account Charges to check various charges charged by leading Demat Accounts like SBI Demat Account, ICICI Demat Account, Motilal Oswal Demat Account, Sharekhan Demat Account, etc. for performing this transaction.
If you think you are not going to use one of your demat accounts and would like to transfer all the shares to your other demat account, you can give instructions to do so while closing your account. My post on Comparison table of demat account charges has a summary of Account closing charges (yes, some DP's may charge you money, something of the order of Rs. 100/- for closing your account).