If a tenant makes alterations or additions to a property, they may or may not be entitled to remove it when the lease ends. Check your lease or license for any information on this. It depends on whether the alterations are fixtures or fittings
Each case is individual but the basic principle is that fixtures form part of the property and belong to the landlord when the lease comes to an end, and fittings may be removed by the tenant. Any tenant intending to make any alterations to the property should obtain the landlord's written consent before carrying out any works, which is usually documented in the form of a licence, which states how the works are to be carried out and what will happen to them when the lease comes to an end.