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Thanks for your interest in the Intel® Edison™ Platform.
I don't think it would be possible to reduce the current, unless you physically cut the power line. I would encourage you to see the datasheet on page 38 http://download.intel.com/support/edison/sb/edisonmodule_hg_331189004.pdf , in order to see the PMIC configuration registers.
Hope you find this information useful, have a nice day!