Here's a breakdown:
* Iwa - to remove
* wala - none
* sa suso - from the breast
Other possible translations:
* Itigil ang pagpapasuso - stop breastfeeding
* Itigil ang pagpapakain ng gatas ng ina - stop feeding breast milk
* Ilayo sa suso - remove from the breast
The best translation will depend on the specific context in which you are using the word "wean".