no, that means if property comes with tenant, then it is sale with tenancy ..
if it comes empty, then its vacant possession..

owners like to sell with tenancy as they usually can get a better price from purchasers who are investors...of course this does not work with
buyers who are buying for own stay in which case, the vendor has to be informed that the purchase is conditional on the property being delivered
with vacant possession

Yes you can, it's your property you have the rights to do whats best.. to me keeping the old tenant are not advisable coz it's like picking up seller/owner old shitz & very risky game.. I prefer empty 

True oso. but I was once offered a corner shop with Hong Leong Bank as tenant. Giv it a pass cos asking price is darn high.