why 70% of memory space of my mac is been taken?

Boot into Safe Mode, and try again.

That will clean up temporary files and will rebuild caches and will shut off some add-on apps.

Unfortunately—if this is a bottom-end Mac storage configuration—available storage probably remains constrained.

EDIT: I would start with MrHoffman's excellent suggestions first.

In theory, macOS immediately frees blocks that are deleted, including system files. It also sends a message to the SSD drive controller (called TRIM commands) telling it which blocks no longer contain useful data and can be re-used. The SSD drive controller is the only device that gets involved in garbage collecting these blocks, re-assembling them into pre-erased super-blocks, and re-using them.

System includes:

• Time Machine local snapshots, but are marked as 'purgeable' and should not be removed manually.
• However, if you wish to do so, use the following commands in the Terminal app:
  • To get a list of current snapshots: sudo tmutil listlocalsnapshots /
  • To delete individual snapshots: tmutil deletelocalsnapshots <enter the snapshot>
• Spotlight Indexing
  • Rebuild the Spotlight index on your Mac - Apple Support
• iCloud Storage of infrequently-used files

FWIW: The TRIM performance-optimization storage command is used by macOS when a file is deleted from SSD storage, and the operation is transparent to the user, and does not effect any displayed allocated- or free-storage counts. TRIM informs the SSD that the user is done using that region of storage, and that storage can then be made ready for quick re-use. SSDs can’t overwrite the same storage (which also means the old-style hard disk drive storage overwrites for data security reasons don’t work the same), and the SSD storage erase operation is comparatively slow, and TRIM is a way to avoid the user having to wait for the erase and the overwrite when some or all of a file is re-written. TRIM is not a factor in user storage usage.

What size disk do you have. I think you mean disk space and not RAM/memory.