I think your output is inconsistent, but the premise of removing preceding characters can be done with the {m,n}
"limiting repetition" clause of regular expressions.
gsub(".{15}Technician", "", dat$Content)
# [1] "21 Inspected parts" "21 Inspected wipers" "22 Fixed wipers "
Note that {15}
will work as long as there are 15 or more characters to remove. For example, nothing is done here.
gsub(".{17}Technician", "", dat$Content)
# [1] "2020-01-01 Car1 Technician1 Inspected parts" "2020-01-01 Car2 Technician1 Inspected wipers"
# [3] "2020-05-01 Car5 Technician2 Fixed wipers "
If you need "up to", then specify both numbers (or both positions) in the range, where an empty slot implies min or max:
gsub(".{0,15}Technician", "", dat$Content)
gsub(".{,15}Technician", "", dat$Content)
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