I have multiple filenames, for example, XXXX_BB_CCCCCCCC_XYXYXY_20180507_123053XMK and YYYY_AA_CJDJD_XY_20180510_134455XMKUY. How do I remove "XMK" and "XMKUY" from the two strings so that I am left with XXXX_BB_CCCCCCCC_XYXYXY_20180507_123053 and YYYY_AA_CJDJD_XY_20180510_134455 only? There are multiple variations from these but basically I just to remove all letters from the last portion of the string.