file an eviction suit against the tenant after serving him a legal notice.
As such that depends on the terms as to when the refund is payable to the tenant. It is usually payable at the settlement of tenancy terms and also it is set-off against the last notice period rent. So, either ways, you would be in a bit of a fix.
First off, reading the terms of tenancy agreement between you and your tenant would be necessary. You can email the scanned copy of the tenancy agreement to my email ID at email@example.com, if you wish to seek consultation.