Removing subtitles doesn't make file sizes much smaller

[Grauhaar]

Subtitles are not huge. They are approx. 20 - 50MB per track on DVDs. Blu-ray subtitles are larger, because they have higher resolution, maybe 100-200MB

To reduce the size of the file you must "compress" the video track with f.e VideoCoder (based on Handbrake) or Handbrake itself.

[streamline1]

Subtitles are often plain text (.srt) or almost (PGS I believe).

In terms of size, in increasing order you have.

Subtitles (negligeable).

Audio (small).

Video (big).

My personal recommandation would be to keep all audio tracks and subtitles, and reencode video with Handbrake if needed. If you can spare the CPU time, x265 is much more size-efficient than x264.

[Woodstock]

DVD and BD titles rarely have text subtitles, other than Closed Caption. DVDs use VOBSUB, BD uses PGS, both of which are picture-based, not text.

Even then, the size does not make much difference.

SRT and Substation Alpha subtitles are text-based, but generally done by fans, rather than the studios producing the disks.