Removing terminal period from varchar string in table column

I want to remove the terminal period '.' from the varchar strings in the
'company_name' column in all rows with that period in the companies table.

I've looked at trim(), translate(), "substr(company_name 1,
length(compan_name) - 1)", and a couple of other functions and am unsure how
best to do this without corrupting the database table.

Advice needed.

TIA,

Rich