You can change the default working units in Maya, which are in metric, but it is recommended to leave them unchanged as some tools in Maya have a set type, for example, Nucleus and Bifrost are set so that 1 unit = 1 meter, regardless of settings. Instead, do not change Maya's default working un its and adjust your grid to align with the scale of the project you are working on. See Working in Maya in different scales for information on how you can change the grid to accommodate working in different scales.
To change Maya's default unit of measurement