There are different ways to do this. A few of options:
Option 1
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Use a text filter on the column, click the 'regular expression' option and in the filter type:
\.$
This will filter to all rows where the last character in the cell is a period '.'
Then carryout a transform on the column of:
value[0,-1]
or
value.substring(0,-1)
Either of these will trim the last character from the string.
Use a match expression to extract everything from the value with the exception of a trailing period:
value.match(/(.*?)\.?$/)[0]
Option 3
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Use an 'if' to test if the last character in the cell is a period, and if so trim it off:
if(value[-1]==".",value[0,-1],value)
Owen