In Italy there are two types of taxes related to properties: IMU and TASI. IMU is primarily a property tax, while TASI is aimed at funding specific local services and can be applicable to both property owners and tenants.
IMU property tax has to be paid using the F24 tax form. If you have an Italian bank account, you can pay the F24 directly from your online banking platform.
If you're unsure of the amount you need to pay, contact the IMU office in your comune (Ufficio IMU-TASI or Ufficio Tariffe) ask them to calculate it and give you the IBAN (bank identification code) for payments from abroad and you can send a bank transfer. You can also contact your local CAF Patronato office for help with this. Agenzia delle Entrate is the internal revenue agency that determines the tax rates for the IMU and TASI as well as other taxes.
Your local comune (municipio office) may be able to help you with an alternative way for you to pay IMU where they can send the payment requests to your address abroad and provide information about how you can process the payment. So contact your local municipio office for information about that.
If you need a copy of the F24 tax form to fill out the details for your IMU payment, you can find a fillable and printable F24 form online at this link.
If you have Italian residency you can open an Italian bank account online with Fineco at this link (in Italian).