You can never evict a tenant yourself. You can only seek a court order to evict a tenant if your tenant is in breach of contract.
To find out if your tenant is in breach of contract, check your agreement. There should be a clause saying what constitutes a breach of contract and what your rights would be in such a case.
If your tenant is indeed in breach of contract, take steps to strongly urge your tenant to rectify the breach. If this does not work, take legal action - lodge a complaint with the Rental Housing Tribunal or seek the help of a competent attorney.