To drain transmission fluid, the general steps are as follows:

1. Prepare by placing a large drain pan under the transmission to catch the fluid. Wear gloves and safety goggles for protection.
2. Locate the transmission fluid drain plug (if available) on the transmission pan. Loosen the drain plug but do not remove it completely at first.
3. Once ready, fully remove the drain plug or unbolt the entire transmission fluid pan (usually 6-8 bolts) to let the transmission fluid drain out. Be careful as the fluid will flow quickly at first and then slow to a drip.
4. Collect all the old transmission fluid and dispose of it properly.
5. After draining, wipe the drain plug and transmission pan clean and reinstall them securely.
6. Check the transmission fluid filter if accessible; replace it if necessary.
7. Refill the transmission with new fluid through the dipstick tube or fluid fill port, following the specific type and quantity recommended by the vehicle manufacturer.

If there is no drain plug, fluid can be extracted through the dipstick tube using a fluid extraction pump. Some techniques involve removing the transmission pan to access the fluid and filter, then flushing the fluid through cooler lines for a more thorough change. It is important to observe proper precautions such as collecting fluid fully and checking for metal shavings that might indicate transmission issues. Following the specific vehicle manufacturer's guidelines is recommended for exact procedures and the fluid type to use.