Are you writing the whole piece with '
I' as the subject, or are you merely including a lot of '
I think', '
in my opinion', etc?
If it is the latter case, the easiest route is simply to delete those
comment phrases. Much stronger writing is produced by saying
Roses are bad for your health instead of
I think that roses are bad for your health.
If it is the former case, you have the options of casting in another person-- usually
we,
people (they) or
one-- or converting much of the text to passive voice, a form used extensively in some genres of formal writing.
Give us an excerpted paragraph of particular difficulty for you, and let us see what is possible.